No, ML won't be revealed but it's hinted multiple times who it'll be. They're a green flag.
The trash boyfriends refer to the MLs in the worlds MC gets transported into. His contract basically makes him go to these different worlds/universes to harvest regret points from the trash MLs. Though as pointed out by the system, MC does something completely different compared to his previous masters/partners. While his previous masters resorted to kissing ass and relying on suicide to farm regret points, MC farms them by making the trash Boyfriends REGRET meeting MC. Like "he ruined my fucking life, i should have never met them" type of regret.
This good? Toxic ML? Cheating ML? Abus1v3 ML? Pls say no