Who is being too needy, me or his girlfriend? Is it worth trying to salvage the friendship?

My best friend, Anthony, and I have been really close ever since we met freshman year. About two months ago he started dating this girl. I was happy for my friend at first, because I thought it would be good for him, but in these past two months I don't even know who Anthony is anymore. He started sleeping over at her place every night, and she expected him to come straight there after classes, etc. Whenever we got to hang out, she had to be there, so that meant we didn't get to really hang out. Anthony and I have already talked about it once, and things seemed to get better, but all of the sudden, no one else can see him but his girlfriend. Most recently, my birthday was on Monday, and Anthony and my other best friend were suppose to bring me out to dinner. Somehow the girlfriend thought she was invited, then acted like she didn't want to be there the whole night, which angered me. I wanted to spend time with my friend, but it seems to me she doesn't want him to spend any time with me. I understand that she is his girlfriend, and I'm just the guy friend, but it is starting to get ridiculous. Any time we plan to hang out, something always comes up with her. Should I just give up or try to salvage the friendship?