If you remember that the MC gets regressed in another persons body. He meets the ML again as becomes his partner who was also his partner in the past before he died.
The MC 's partner before the ML who everyone believes is dead and the MC suffers sooo much bcz of that. But that partner is actually not dead.
The ML actually believed that MC will return bcz his partner who is alive is obsessed with him. And he will bring back the mc somehow.
It was the partner who killed the MC by mistake whem MC and the ML was on a mission and his target was actually the ML.
Now the MC also figured it out that his partner faked his death and betrayed him.
I hope you dont mind revising this cause some parts were confusing even to me who remembers almost everything - just due to all them using the same pronouns lol (the woes of mlm)
MC (MC1.0) is murdered then gets 'reincarnated' into another guides body (MC2.0)
MC and ML were partners before the reincarnations and become partners after as well.
MC1.0's previous partner (The Ex) died before the ML and MC1.0 met in the past. Its a v triggering moment for MC1.0 since they were gay as fuck and iirc also the same accident that gave MC1.0 the knee injury? We find out close to the end of s2 that The Ex either faked his death or /also/ reincarnated like MC did.
The Ex was the one who killed MC1.0 but it was a shot meant to actually kill ML that missed.
ML is yearnertron fag-thousand for MC1.0 and s2 final revealed that he knew MC2.0 is the reincarnated MC1.0 for a long time but pretends not to know in front of MC2.0.
(Note: Im gay im allowed to use my funni slur for jokes)

I actually forgot some points of the story. Like could someone help summarize it for me please