A good friend went through the exact same thing with her man... He was fine when it came to cuddles or kisses, but sex was never on the cards. She tried pretty much everything to get him interested, and that was basically the problem.
He knew he could get it any time he wanted, there was no build in desire because it was there waiting for him at all times, and every time he went near her, he felt she was trying to direct things towards sex.
It became far less problematic to just go look at porn and have a wank.
Now there's no way for us to know why your man is doing it, we're not in the relationship and we don't have the benefit of being able to ask both of you for your version of events, but you've made it pretty clear you want sex, and your comments are more to the effect that you feel inconvenienced by the lack of sex than concerned about why and my guess would be that if you've managed to convey that her in such a small space of time, that he's probably feeling it even more.
He obviously wants to connect with you on some level, maybe he just feels that you expect to be getting sex regardless of if he wants it or not (whether that happens to be true or not) and as such feels too much pressure and turning to porn to get what he wants, when he wants it, without getting himself into a situation where he feels he can't give you any affection without it leading to sex.
I happen to think it's a pretty dumb way of looking at things, but from what I've seen/heard with others, it isn't exactly uncommon.