I know her bf is having an affair. Should I tell her?

[fmerchant]

Just over a year ago, someone I know moved to London from Canada with her boyfriend. Since arriving there, her bf took up Russian language lessons - a group class taught by a Russian female. This seemed like an interesting thing to do but he has a bit of a thing for Russian women. This hidden reason has now become reality. Over the course of the year he has become very friendly with his Russian teacher to the point that they message and speak throughout the day every day, hang out together regularly and have become very close. Now they have grown inappropriately close and are having an affair. I feel its my duty to somehow let her know… Should I?

[bathtub-row]

Yes! As long as you know for a fact this is going on. It’ll hurt her but she needs to know. If she finds out that you knew this and kept it from her, she will probably be very unhappy with you.

[d0nnivain]

I'd tell her the facts as you understand them. Tell her in a matter of fact manner, along the lines of "it were me, I'd want to know which is why I'm speaking up." Then support her in whatever decision she makes including the decision to stay. If you can't abide that, just fade out of her life but don't sit there & bad mouth the BF even if she is.

[Gaeta]

How do you know they are having an affair?