I'm looking CN BLs like "The Demon Lord Only Wants to Follow the Script"....... It should have a MC who was brought to another world by a system and needs to complete a specific task as according to the script, and after completing the script will just leave the scene to live normally. Also the task should have something to do with ML and while doing the task the ML falls in love with MC but MC doesn't know and will leave after completing the script then ML will go crazy looking for MC. I would prefer if the script requires the MC to die (in front of the ML)..... The ML will find the MC and they'll get together after getting everything straightened out and getting rid of all the misunderstandings between them. There should be angst somewhere in the middle and everything should end HAPPILY EVER AFTER!!!
The Scum Villain’s Self-Saving System Transmigrating into a Mob Character to Rehabilitate the Villain Plan Where is Our Agreement to be Each Other’s Arch-Rivals? Heroic Death System The Icy Hero is Yearning for Love (Japanese but kinda fits the bill of what you're looking for) Pulling Together a Villain Reformation Strategy (Almost completely translated) After Transmigrating Into The Weak Villain (Almost completely translated) Also here's my rec list maybe you'll find something you fancy https://www.novelupdates.com/viewlist/51191/?st=1&pg=3