Need relationship advice (NSFW-ish)

So, I'm in high school (incoming junior), and I've been good friends with this other guy in my grade since middle school, and we're both gay. We're not dating or anything, but earlier this summer we lost our virginities to each other just to see how it feels. We hooked up once more since then, and due to various vacations and summer camps we haven't seen each other in almost a month. Our sexual relationship has continued over text though, and we've developed a kind of master-slave alter ego relationship. He tells me how bad he wants my cock, I tell him how bad I want to fuck his tight ass... you get the idea. The thing is though, every time after we have one of these conversations, the next morning (or sometimes even immediately after) he tells me that he thinks it's wrong and we should stop, since we already found out what it feels like, which was the whole point of having sex in the first place. But then, a day or two later, he flips back, saying it's just pleasure, no strings attached, and justifies it for himself. But it's back and forth, like clockwork. I've repeatedly said so, but he just brushes me off every time and says that he's fine with it. But then the next time we have a sexual convo, he immediately tells me how much he regrets it and doesn't want to screw up our friendship. I've told him that if he wants to hook up again I'm open to it, but if he's uncomfortable with it, then we can be just friends and that's fine too.Sorry for the wall of text, but that's my situation at the moment. Any advice for how I can help him out or resolve the situation or whatever will be greatly appreciated.