Am I being stupid?

So, basically. Been going out with my bf for about 4 months now and it was going good, apart from a couple of dips. However, recently we were going to go out for a day, and then he waited until two days before to say he couldn't afford it / didn't want to go. We were supposed to be going to a party this weekend but he told me yesterday that he couldn't go because he had an exam the next morning. Now had he told me this two weeks ago when I had first mentioned the party, or over the last couple of weeks when I had been saying about going, then I wouldn't have really minded. But the fact I had started looking forward to it and believed he was actually coming, for him to say no I'm not coming, I was a bit pissed off. He said he hadn't told me because he had been distracted, but he could have told me 2 weeks ago. Am I wrong to pissed off at him? Also, recently, it feels like he doesn't listen to me I tell him something and then he's forgotten the next day, like I'll ask him how his exam went and then when my exam comes round he'll be like, oh yeah, which one was it? When I had told him the previous day. Also it's starting to feel like he just wants me for sex, every week its like I'll go round his, we'll have sex, he'll play his games for a while, then I'll go home. Is it just exam stress at the moment, or have I done something wrong? I'm just feeling a bit depressed at the moment. :(

Put the internet to work for you. via Personal Recipe 2629979