Just can’t get over my ex...

I am a 25-year-old guy and was madly in love with my girlfriend, whom I have known since we were in college. We were together for almost two years until I found out that she had been cheating on me and dating someone else for a few months. It hurt me in ways I cannot fully understand yet. We broke up almost a year ago, but I have not been able to move on. I think about her a lot and can’t come up with a single reason why she would do that to me. I always thought she loved me and saw no signs or indications. I want to move on but can’t because I don’t have answers to the many questions that keep me up at night. What should I do?
You have to acknowledge and accept that you are in pain and need time to recover. This is a slow process because you have been deeply hurt, and you may never have answers for why you were cheated on. People are complicated and have all kinds of reasons for why they do the things they do. This may have nothing to do with you and everything to do with what your ex-girlfriend wanted. If she hasn’t given you a reason, you can’t be hard on yourself and imagine possible scenarios because they aren’t based on facts and serve no purpose. It’s okay to be in pain, and the thing to do is allow yourself to grieve even if it feels as if you may not get over this. There will come a time when it won’t hurt as much, and you have to be patient enough to accept that.

How do I know why my girlfriend is always finding fault with everything I do? If she doesn’t like anything about me, should we just assume this relationship isn’t working?
If she can’t articulate what the problem is, and you can’t figure it out, your inability to communicate will eventually prevent this relationship from evolving.