Bf stares at my new bff

hi alllll, so my boyfriend and I just relocated and we made a new friend group. It’s another couple and he’s gotten close to the boyfriend and I’ve gotten close to the girlfriend. Recently I’ve noticed him just blatantly watching her. We both do the same sport and practiced together the other day. It felt like his eyes were glued on her and after her rounds he’d say good job or something stupid. I’m just starting to get a little irritated hanging out with them because it bothers me to see him sort of obsessing over her. I know he would never cheat and she wouldn’t cheat on her boyfriend, but it’s just bothering me. I had this issue with the way he looked at her when we all first started chilling and he told me I’m putting intent behind his actions... I’m just feeling lost and kinda upset. Definitely over nothing but I want to vent and tell him it upsets me.... what are your thoughts?