Boyfriend best friend problems???

So I’ve been dating my boyfriend for almost 10 months, and a friend we shared introduced us and we totally hit it off. After a week or so of us first meeting he asked me out on a date and things have been pretty great! But the friend that introduced us is rude to me when my boyfriend is around (he’s practically my boyfriends best friend) and purposely tries to get us into a fight. He tells my boyfriend things like “that’s not how I would let my girlfriend act” or at one point he even claimed I was flirting with him and other guys.

But when we are alone he likes to hit on me. He even told me I have the nicest butt he’s seen. And my boyfriend talks about how all his friends want to get with me....

But it’s getting really annoying at this point because I claimed that i think it’s attractive if some guys pierced their ears, and more than a week later he got his ears pierced..... then I showed my boyfriend a cool tattoo in another language that he should get, and his best friend decided he would get the same tattoo in the same place but just make it a different word.

Why is this happening? I’m really worried this feud could ruin my relationship. I’m so not amused. Like is this his way of trying to get with me? Or does he just hate me so much he’s trying everything to get me and my boyfriend to break up? whyyyyyyy