Most Helpful Girl
How are you so sure you are in love with your ex? Sometimes, we tend to idealize the past and make it better than it was. There was a reason you lost your feelings. Either the relationship wasn't right or you were holding yourself back. I have a feeling that if you were to go back to your ex, the same thing would happen again. Do you really want to put him through that? Put yourself through that? There really is no easy answer here.
I think maybe it would be a good idea to examine your ideas about sex. You said you started losing your feelings for your current boyfriend after that, which may be the cause of your loss of feelings. Can you tell us why? There may be something there, something that causes you to shut down. Some kind of trauma, ex: your parents divorcing . Or you feel there is too much intimacy and you feel too vulnerable. We can sometimes fear being vulnerable and sex can be something in which we are very, very vulnerable. (hahaha sorry I'm a psych student. We love analysis! :)).
Perhaps the simplest answer is that neither of them are right for you. On some levels you are connecting with them, but on others you are disengaged or you don't mesh well with them. Ask yourself what it is that you really feel you are missing in your relationship.
Maybe you are feeling pressure by both these men. They both have said "they think you are the one." On some level that may be making you withdraw your emotions from these men because you fear failing them or disappointing them in some way.
Only you can truly know the answer to your question. Perhaps you should stop thinking about what you "should" or "shouldn't" do and just be. The answer will come. All you are doing right now is thinking yourself into a tizzy and preventing yourself from coming to a conclusive decision. The answer might be just to be alone until you can figure this out.
Best of luck and I know you can do this!