Getting very frustrated

So lately (the past month or so) my boyfriend had barely wanted to have sex with me.. I didn't know why. Until tonight... Apparently it's because I won't give him a bj.. Up until a few months ago I had never even done that. I don't really like to but I will

usually do it when he asks.

But the way he said it tonight basically sounded like if I didn't we weren't having sex tonight.. So eventually I said ok. And he just kinda sighed and hadn't said anything since.. Wtf... I agree to what he wants and still he won't have sex with me...

Other than this he has been distant and hiding his phone. And taking it everywhere with him.. He literally never leaves his phone near me when he's not in the room..

What did I do? I feel like something else is going on but I don't know what... I'm tired of feeling like he doesn't really want to be with me..

Please any advice???