help me figure this out

so I've got a friend 17(F) we've known each other since 6th standard. shes in a relationship rn earlier I used to like her and we talk on a weekly basis now here's the problem she sends me her photos some are decent some are really hot like in shorts and bra etc now ik she's a attention seeker but I (17M) can't help it cuz she's super hot and i appreciate the photos yk but I also feel bad for her bf . Recently I've noticed myself wanting more of those photos from her like I don't ask outright but I want them. HOW DO I GET OUT OF THIS CYCLE.