What I remember from description: MC is rebirth. In the past life, he loved ML very much but ML didn't like him. Either he obsessed with ML or he would do anything for ML, I don't remember which one. In this life, he gives up about ML and not bothering ML anymore. Turns out ML is rebirth too. In this life ML wants to treat MC well but MC doesn't care anymore. There's a line from MC like this in the description : "so you like it when I don't love you"
This one is definitely on NU, I can remember seeing it. Can't recall the name but it's listed so you will find it if you look.