Need some advice

My boyfriend and I have a great relationship. But there is one thing I am a little annoyed about. He has this "cousin" that is not really a cousin just family friends. His sister hooked up with the brother of this "cousin". He has called her attractive to me. He also liked a few of her Instagram pictures and I know that sounds CRAZY! But he doesn't like anyone else's pictures like at all. Yesterday we were at a party and this "cousin" was there and while my bf and her talked he had big puppy eyes. Oh and when she was leaving they shared a hug that was just a little too long... Also her contact was "my future wife" until I saw it and asked about it.. I feel like I sound crazy but I'm just really bugged by it all and would love some other opinions PLEASE 😘