Recommendations BL where ML has a girlfriend/fiance, etc. in the beginning

It can be manhwa or novel as well. I am looking for something where the ML and MC already knew each other for quite some time, maybe since childhood. I don't want the ML to romantically like the MC from the beginning, I want him to go through a discovery/jealousy phase. I want him to actually like the girl he is with in the beginning. And MC pining after him, maybe looking for someone else, just to find ML jealous.

Just like Rocket Science Love. I really, really love it.