What should I do? Should I just ignore my best friend forever?

I'm a guy and I've been best friends with Alex for 8+ years. Ever since he has a girlfriend he's been spending so much time with her. I myself have never been in a relationship so I'm kinda in a bad position. Every time I ask him if we can hangout he always picks his girlfriend over me. By the way his girlfriend is my cousin. Stage 3 Honeymoon? I don't want to hangout with the couple because it makes me feel VERY uncomfortable. So in the end I'm choosing to end our friendship that's what I think is best for me. It hurts me too much that a best friend I've known for 8+ years would do that. I don't mind them dating but if he's going to do that to me I wouldn't want to be friends with him. Let me know your thoughts and I'll reconsider