my (m20) girlfriend (f20) regularly rubs a guy friend’s back and i’m uncomfortable, how do i resolve this issue?

we’ve had this conversation a while ago but recent events made me think of it again.

she claims that rubbing someone’s back is a purely platonic thing which i do believe, but when i asked her who she did it to, she mentioned a guy friend that she really likes (platonically) who had actually asked her out on a date when they first met. think i should mention here that we’re in a long distance relationship. the conversation ended with her saying she’d cut back on this because it bothers me, but she couldn’t completely stop rubbing backs.

still really really bothers me to this day. i believe her that there’s no feelings involved but i can’t shake off the intense feelings of discomfort i get whenever i think about this. how should i approach this issue?

it’s also just really heart aching because her back rubs felt so loving. the fact that she did it to other people was oddly devastating.

i’m only intimate with one person in my life—her. it feels weird that she isn’t, even though i can’t expect her to just be intimate to me. but to another guy that was/probably still is attracted to her? it hurts.

do i bring it up with her again? it would only stress her out, i dont even know how bringing it up would help. that’s why im here on reddit.

i’m really serious about her, so i dont even want to consider breaking up.

should i be bothered by this? if the comments are more radical than i expect id probably just send this whole post to her tbh