best friend has a boyfriend

I'm feeling really down and sad because my best friend has recently got a boyfriend. They've been together about 3 months now and she's spending alll her time with him, and always asks to bring him to our girls time etc. I feel like I'm loosing her and getting more annoyed with her as their relationship goes on. It doesn't help that I think the boyfriend is a complete asshole too. 😢 anyone got any tips on what I should do??