Thank you for that additional info. Without talking to him, it would be impossible for me to say why he feels this way. It could be so many different reasons, a short list would be
he was abused, sexually or otherwise
he has been cheated on or hurt by a woman or women
he's bisexual or homosexual
there could be other reasons but as I said without knowing much more about him and his past I can't be sure
The fact is, whatever the reason, you have to decide if you can live like this. Ask yourself, what if six months from now, things haven't changed, will you stay with him? What if things don't change in a year, will you stay with him? Do you have enough feelings for him to stick with him through whatever it is he's struggling with?
Two months is not enough time to know someone that well, as you can see, he's not even sure why he's like this (so he says) so how can you be expected to understand. If he's willing to go into therapy or counseling immediately to try and figure this out, I would consider staying with him, but if not, I don't think things will change, and if they do, there's no guarantee it will last.It really depends on him and how willing he is to change what's going on with him.
I welcome your thoughts, let me know if you want to talk more.