And I have to agree with opinion on the two friends. As much as I enjoy reading this they were terrible friends and don't really deserve the MC's forgiveness.
That being said, this story focuses quite a bit on their redemption as they realize their mistakes and the horrible consequences that they caused. While the MC forgives very quickly, he doesn't really remember much and so the impact of what he suffered because of them is greatly reduced. It makes the forgiveness much more reasonable since he truly doesn't recall the things that caused his depression. As a reader though, I hope that in the end neither of the friends end up with the MC. They both obsessed over him, tried to isolate him, and took advantage of him. This eventually led to the MC's ruin as he was unintentional ruined by the selfishness of two closest people in his life.
And when the light in his eyes dimmed and he lost his bright personality they left him. Put of by the change in his character they never bothered to find out why he changed. And when rumors slandering his character were spread around they chose to believe them instead of discovering the truth. In the original timeline the MC commits suicide after being strung along, isolated, and used by what he believed to be his friend and lover. So now that the MC has lost his memories and regained his bright personality they both flock to him again. They are slowly learning the truth about the MC prior situation and feel regret. And while I appreciate their remorse I feel that they don't deserve the MC and that their selfishness will only ruin him again. I really hope he ends up with one of the other love interests as they seem to actually care.