When something in a relationship goes wrong, one may try to label their partner with a mental illness to explain why it didn't work. You don't have the ability to diagnose your ex, nor can a mental illness be the sole reason why someone no longer wants to be in the relationship. It sounds like your ex may the type who holds little things in (things you did that bothered him) and then kind of blows up when he can't take them anymore. A lot of people do that, especially those who are more shy or who don't like confrontation. You may have thought everything was fine because he wasn't telling you how upset he was getting until it became too much. It does sound though like he did-- at the end-- tell you about the things that had been eating him up inside. So the relationshup did not feel as smooth or happy to him as it did to you. If he has made up his mind, then there isn't really anything you can do about it except move on. Sometimes, when you're dating someone who is shy or doesn't like confrontation, you can encourage them to share how they're feeling or ask if anything is bothering them gently. Giving them space and opportunity to share night help, so they don't bottle things up as much. I realize it can be frustrating to date someone who holds things in, but you can't change the other person (only yourself). Or you may realize you only want to date people who are more foreward.