Help! Is my boyfriend into his cousins girlfriend?

So the last couple months I've been noticing more and more that when I'm hanging out with my boyfriend and his cousin and his cousin's girlfriend that he like pays attention to her a lot. Like he talks to her, or like when she's talking to her boyfriend he like watch them and listens to what their taking about and laughs at everything she says/ dose. And when he calls his cousin she answers the phone most of the time and he always seams really happy and laughing a lot and stuff with her. And they like txt each other sometimes and stuff. And tonight we were somewhere and then I took my car home and they all went in his car together and I was listening to Spotify (me and my boyfriend share an account) but you can only  listen on one phone at a time. And my music stopped playing like 5 minuets after I left so I looked and it said he was listening on his phone so I thought nothing of it. But I checked back like 20 minuets later and they were still listening on his phone but I noticed it's weird music that isn't his type at all. So I checked and she made a playlist on his account with her name and everything and is adding song after song on there (he is driving) and the thing is. My bf is kinda picky about music, if we're listening to my music he skips more then 1/2 my songs because he Dosent like them. But he's just letting her make a whole playsit of music I know he Dosent like and letting her play whatever.... Ik this is kinda long and rant-y. Sorry guys! But dose anyone have any advice? Do you think something is happening here or am I just being paranoid?? Please someone help!