I don’t think he was threatening him to commit suicide it’s more like because MC decided he would dedicate his life to getting revenge and such then ML saw that he would do it for him too(sarcastically). I will admit it was unhinged as hell but he does care for the MC he was just extremely upset that his partner would rather die than be with him because of his guilt of the past. Guilt he was helping the MC get over and asked multiple times what would it take for him to move on so it isn’t like he is not aware of the weight it carries. He just took advantage of that weight to force the MC to take him more seriously. It is immature and a really bad way to do shit like this tho.
Trapping someone with the threat to commit suicide is simply a big NO.. Get a therapy dude..