How do I [28M] evaluate whether trust can be rebuilt after a complicated start with my girlfriend [20F]?

[MKF]

My girlfriend [20F] and I [28M] have been dating for three months. We explicitly agreed to exclusivity last month.

Then we were away for 2 weeks. After she returned to her city (i was still away) and, obviously, after the exclusivity conversation we had, she arranged to meet a man she had been emotionally and sexually involved with before me and hadn’t closed things with. From what she wrote at the time, it appears she intended this to be their final meeting and was already trying to end their unhealthy attachment. She had even prepared a goodbye letter.

Nevertheless, they went drinking, returned to his apartment, and had sex. She went back the following day as she had forgotten her ring, and they had sex again.

The arguments in her favor are:

* She was leaving a complicated and possibly manipulative attachment, rather than beginning a new affair.
* Before I confronted her, she had already decided internally that she needed to end things with him.
* The meeting seems to have been intended as closure, even though she failed to follow through appropriately.
* Since the confrontation, she has ended contact, accepted monogamy, apologized, and appears genuinely committed to changing.
* She says she cannot repair the past but wants to make things right in the future and does not want me to stay out of pity.
* ⁠She was constantly manipulated by that man she met, and she had trust issues towards men because of what she experienced in the past

The arguments against her are:

* We had explicitly agreed to exclusivity before she met him.
* Whatever her intention for the meeting, she still chose to go home with him and have sex.
* Returning the following day makes it harder to view the first encounter as one final mistake.
* She initially concealed or denied important facts.
* She herself considers it cheating and has said that, in my position, she probably would have left.
* Cheating has always been a firm boundary for me, and I worry that resentment and intrusive thoughts will prevent me from genuinely rebuilding trust.

I love her and believe the situation was more complicated than ordinary cheating, but context does not erase the agreement she broke. I also do not want to stay only because I am attached to her, nor leave automatically if genuine repair is realistically possible.

Given both the betrayal and the surrounding context, how should I decide whether to stay and attempt to rebuild trust or leave the relationship?

[Sanch62]

How did you find out about this? You mentioned that she wrote something, what is that about?

[Sony12]

She clearly isn't over him. If she was truly over him she never would have agreed to meet him again.

 

[ExpatInItaly]

10 hours ago, MKF said:

I love her and believe the situation was more complicated than ordinary cheating,

It's not, though. It's ordinary cheating. 

She should not have been meeting up with him in the first place. The very fact that she followed through wih that is bad enough, as it tells you where her feelings for him were (she wasn't over him) She then cheated not once, but twice. Neither the first nor second time was a mistake. It was intentional, not an accident. 

From someone quite a bit older than you? It would be foolish to stay with her and this won't end well for you. She isn't ready for the relationship you want, and does not respect you or feel strongly enough about you for this to work. 

[Sony12]

Yep. Her willingly going over to his place was a clear sign that she was open to something still happening between them. 

It was probably too soon for you two to become exclusive given that she is only 20 and is clearly still trying to get over an old flame. You may be better relationship material for her than her last boyfriend was but that often isn't what late teens and early twenty something's want. They often want someone who excites them.

Edited August 4 by Sony12

[MKF]

She struggles to close relationships in general. She had met me and we were dating and had sex multiple times when she was still with this guy. Also, the same thing happened with this guy when she first met him, she had not closed things with her older ex. I know what she did was big, but is the fact that the relationship was early and not yet very well established give a reason for continuation? Can I say that this was not ordinary cheating given her history and the fact that the relationship was not well established yet? Should I take into account the fact that she is really changing and has showed it through action? Can respect be there if i continue from here or is it permanently damaged?

Edited August 4 by MKF

[Gebidozo]

22 hours ago, MKF said:

I love her and believe the situation was more complicated than ordinary cheating

I’m sorry, but no, it was ordinary cheating.

 

22 hours ago, MKF said:

Given both the betrayal and the surrounding context, how should I decide whether to stay and attempt to rebuild trust or leave the relationship?

It’s your decision. I would definitely leave.

[Sony12]

3 hours ago, MKF said:

She struggles to close relationships in general. She had met me and we were dating and had sex multiple times when she was still with this guy. Also, the same thing happened with this guy when she first met him, she had not closed things with her older ex. I know what she did was big, but is the fact that the relationship was early and not yet very well established give a reason for continuation? Can I say that this was not ordinary cheating given her history and the fact that the relationship was not well established yet? Should I take into account the fact that she is really changing and has showed it through action? Can respect be there if i continue from here or is it permanently damaged?

So she originally cheated on him with you? If you are looking for an actual relationship this is not a girl you will find that with (at least not at this stage in her life).

[MKF]

8 minutes ago, Sony12 said:

So she originally cheated on him with you? If you are looking for an actual relationship this is not a girl you will find that with (at least not at this stage in her life).

Thank you for your replies really . Yes she cheated on him with me. Before that she cheater with him on her older ex. After out exclusivity conversation she was really moving towards ending things with him, and was really changing, but maybe because this behavior was normalized to her internally because of what she used to do in the past she did this. After the confrontation she has shown signs of actual change. My main question is: can this be framed as that the relationship was not yet established and it became clearly established after the confrontation, and we try from there? Or is this a false framing?

[flitzanu]

4 hours ago, MKF said:

She struggles to close relationships in general. She had met me and we were dating and had sex multiple times when she was still with this guy. Also, the same thing happened with this guy when she first met him, she had not closed things with her older ex. I know what she did was big, but is the fact that the relationship was early and not yet very well established give a reason for continuation? Can I say that this was not ordinary cheating given her history and the fact that the relationship was not well established yet? Should I take into account the fact that she is really changing and has showed it through action? Can respect be there if i continue from here or is it permanently damaged?

unfortunately you need to recognize this as a pattern. 

it doesn't make her a bad person, but it certainly shows that she doesn't seem to have boundaries about relationships and likes to cheat on people.

[Sony12]

She is in no way ready to settle down with one person.

[ExpatInItaly]

She's a serial cheater. 

You've already seen the consquences of choosing to be with someone who lacks a moral compass and maturity. You were perfectly aware that she cheats, and what do you know, she cheated on you too. 

Stay if you want but know that this isn't going to be your Happily Ever After. This will be temporary until she meets the next guy she likes more than you. 

[ShyViolet]

So you and her had an exclusivity conversation, and then the first thing she does is have sex with another man two days in a row.  That doesn't bode well for the relationship.  There was no reason for her to be meeting him "for closure."  That's nonsense.  She lied to you when she agreed to exclusivity with you.  She is not ready for a relationship.

You also sound like you are making a lot of excuses for her.

[MKF]

9 hours ago, ExpatInItaly said:

She's a serial cheater. 

You've already seen the consquences of choosing to be with someone who lacks a moral compass and maturity. You were perfectly aware that she cheats, and what do you know, she cheated on you too. 

Stay if you want but know that this isn't going to be your Happily Ever After. This will be temporary until she meets the next guy she likes more than you. 

I was not aware that she cheats. I knew all of this information together all of a sudden

Edited August 5 by MKF

[Sanch62]

10 hours ago, MKF said:

I was not aware that she cheats. I knew all of this information together all of a sudden

How did you find out?

[MKF]

1 hour ago, Sanch62 said:

How did you find out?

Someone close to her told me

[ExpatInItaly]

13 hours ago, MKF said:

I was not aware that she cheats. I knew all of this information together all of a sudden

Even worse - you didn't really know who you were dealing with. 

Why on earth would you stay? Are you particularly lonely, or...? 

[Sanch62]

2 hours ago, MKF said:

Someone close to her told me

When you asked her about it, what did she say?

[MKF]

2 hours ago, Sanch62 said:

When you asked her about it, what did she say?

She tried to deny at the beginning but when i pressed she admitted everything. Her friend also told me that she was genuinely choosing between me and the other guy and had decided to close things with the other guy but she was just struggling to close it and that she would eventually do it. She had even written him a letter to end things

[MKF]

2 hours ago, ExpatInItaly said:

Even worse - you didn't really know who you were dealing with. 

Why on earth would you stay? Are you particularly lonely, or...? 

No, i just know that she had trauma from past relationships and that is why it wasn’t easy for her to close all options as it would psychologically put her at high risk. I also know that she was originally choosing between me and this guy and she had decided to close things with him but of course she did not follow through quickly. I also know there are a lot of red flags so I did not decide yet that I am staying. I am just making sure I am thinking properly and considering all factors before deciding, and I am leaning towards leaving.

[ExpatInItaly]

8 hours ago, MKF said:

i just know that she had trauma from past relationships and that is why it wasn’t easy for her to close all options as it would psychologically put her at high risk.

No. 

Trauma doesn't make people cheat and lie. You are twisting yourself into knots here and coming up with whacky theories to explain her behaviour. Her childhood trauma didn't hold a gun to her head and send her into this guy's bed. And it sure didn't pick up that same gun the second time and lead her to do it again. 

She is not relationship material at this time in her life. Stay away from anyone "struggling" to choose between two people. It means she wasn't into either one of you enough and lacks the moral fibre to behave repsectfully and sort herself out first. 

[Sony12]

She's likely cheating because she's horny and enjoys having a lot of different sexual experiences at this point in her life. It's not like she is feeling stuck in an unsatisfying marriage or anything like that. She's cheating because she simply wants to get laid.

[flitzanu]

11 hours ago, ExpatInItaly said:

No. 

Trauma doesn't make people cheat and lie. You are twisting yourself into knots here and coming up with whacky theories to explain her behaviour. Her childhood trauma didn't hold a gun to her head and send her into this guy's bed. And it sure didn't pick up that same gun the second time and lead her to do it again. 

She is not relationship material at this time in her life. Stay away from anyone "struggling" to choose between two people. It means she wasn't into either one of you enough and lacks the moral fibre to behave repsectfully and sort herself out first. 

exactly this.

mental health should be respected, however, it doesn't give a person free reign to lie and cheat to committed relationship partners.

[ShyViolet]

On 8/5/2026 at 5:14 PM, MKF said:

No, i just know that she had trauma from past relationships and that is why it wasn’t easy for her to close all options as it would psychologically put her at high risk. I also know that she was originally choosing between me and this guy and she had decided to close things with him

Trauma from past relationships is not an excuse for cheating.  This is nonsense.  You seriously need to stop making excuses for her.

[Sanch62]

If you want to pretzel yourself to keep someone who is so hung up on someone else that she can’t resist sleeping with him, then go ahead. It’s not against the law, but it won’t buy you any peace the moment your back is turned.