wtf just happened , can sm1 please explain this ending to me???

The easiest way I can explain is that our MC is actually the game version. And the game version is the actual MC. They accidentally got switched when they were young until now. Since our MC is now back to his own world which is the game, has sacrificed himself and was stuck in limbo for a long time.

The ending shows the ML meeting up with our MC who has no memory of the ML or the past life they had together. Meaning by the ML has regressed again, all to see his lover.