Insecure, NEED ADVICE

there’s this girl who is super nice and I really like her, but I know her and my boyfriend talked like a year ago and I don’t even think it was anything more than friends.. even though I think he had some feelings for her. They have a lot in common and everything and sometimes I just let it get into my head. Every time we all hang out in a group it seems like he always laughs at everything she says and talks to her all the time, but I’m not sure if that’s just because I’m looking out for it and let it go into my head. He doesn’t treat me any different when she’s around though, he still will hug me and hold my hand.. etc.. and he’s told me he doesn’t look a anyone else like that & he knows he’ll never be able to open up to someone like he has with me. But it still just gets into my head and worry that he thinks she’s more fun than me and would rather have her even though he says he doesn’t I just don’t know. They don’t talk or anything outside of when we hang out, but he’s not the type to randomly start conversations. And sometimes if someone mentions something about her he has to always say something back about it and I feel like he does it to make me upset. Please comment what you think!!