I don't know that any of this is a mental illness, sometimes it boils down to personality as well. We are all still people and even if you have a mental illness like bipolar, we all just don't act alike.

Sound alike this guy does have issues tho. Not wanting to ever offer anyone an explanation for anything~ while we don't owe people explanations, it is a part of communication. Honestly sad to say, but it sounds like you are probably better off without this guy. It doesn't sound like he really has anyone's interests in mind besides his own. That doesn't make good relationship material. As a relationship is about both people involved not just one.

I think if I were you I would just focus on moving on, and finding someone who is a better fit, an actually wants a relationship~ since that's what you want. I'd not worry over if this is a mental illness or not. That's not something anyone cam answer, and even if he does have a mental illness, personality and personal traits still play a large role, just like anyone else.

I wish you the best!