I'll keep this as brief as possible, and am only posting so I can handle this in a respectful way.

My girlfriend of a couple years is on a trip with some friends in a beachy location. She's been gone for over a week now, and last night sent me a picture of her in a bathtub. You could only see her legs, but almost all the way up. We sent a few flirty texts back and forth, and that was that. I took care of some chores in our apartment, before sitting down and scrolling on my phone. When I opened instagram, I saw my girlfriend posted the bathtub picture on her story. I wasn't a fan of this, not so much because she was exposed (it's really just her legs, though again goes quite high), it's more that she sent it to me as a sexy picture but then posted it on her public account.

A couple hours later she sends me a screen shot of some guy I don't know responding with heart eyes, saying "you are stunning". Also in the picture were his comments on every story she's posted since being on vacation. All were comments on her looks/body, except for one which was just a picture of the beach. I could see that she hearted this comment. She immediately texted back that it was meant for her best friend (her and I have the same initials which has led to some cross-texts).

I have a few issues with all of this, but want to make sure I handle it correctly. Firstly, I don't love being sent a "sexy" picture that's just going to be shared with everyone. Something about it just rubs me the wrong way. Secondly, who is this guy? He could be some creepy rando. In fact I think that's what it is based on: he follows her/she doesn't follow him. But she clearly liked one of his responses AFTER he was incredibly inappropriate.

My feelings are she liked one of his comments to not escalate the situation, and was sending the screenshots to her friend because they're so creepy. But I just don't know, and again want to approach this correctly.

Thank you!