Honestly, I have no idea, I've never met the man. I can tell you that I learned patterns of behavior at an extremely young age, designed to push people away from me as a means to cope with anxiety, and that these behaviors became compulsions over which I had little to no conscious control.
Extreme amounts of anxiety can be overwhelming. That words gets tossed around a lot but think about what it really means. Anxiety can overwhelm you to the point where you have no mental energy left to think about or deal with anything else, and all your strength is going to just dealing with the anxiety.
None of us know though. Ask him? If he won't tell you, do what you can to move on with your life. Regardless of what happened with him and why, relationships are meant to teach us how we need to grow, so I suggest you use this to learn about yourself. Obsessing over things you cannot know the answer to, such as whats going on with another person, when they might not even know themselves, do no one any good. I know, I've spent far too much mental energy thinking about that stuff.