
I can't think of ANYTHING worse than being in your position. I'm the same way when it comes to having to break up. I don't want to hurt someone's feelings....but then I end up being distant....which is equally (if not worse) of a pain to someone else.
Normally though, you aren't doing anyone any favors by vaguely holding onto a relationship. Actually, you are keeping them from moving on and maybe finding someone who DOES love them and can make them happy.
No matter what your mental state was in....would YOU want someone to stay with you if they didn't want to be there? Then, if you found out later about what a long time it was that they wanted out before you found out....that would be even worse than if the person had just come face to face with you and had been honest in the first place.
Again, I'm not good at break ups.....but there is always a time you have to do what you have to do. The longer you put it off....the longer BOTH of you are unhappy and can't move on.