Make the main character one of two guys vying for the attention of one girl. The girl likes both of them, but is slowly growing more and more ragged and emotional from trying to pick between the two without hurting anyone.
Ending 1: Talk with her, and let her know that you're fine with whatever she chooses. Actually, nudging her towards the other guy, just to end her suffering, because it hurts more to see her suffering then to not be able to be with her.
Ending 2: The girl goes crazy, and stands at the edge of a roof, with the intentions of ending it all. Both guys are there, and both lunge a her at the same time to stop it from happening, but instead all go over the side. Main character flips himself underneath to cushion her landing, both the girl and the other guy survive, and MC gets a blissful sense of happiness that she's alright, and she doesn't have to choose anymore as MC passes on.
Ending 3: MC gets crazed with desperation to just end her pain and the need to be with her. Kill the other guy, making it look like an accident. MC breaks down and cries to the heavens for forgiveness, but never tells the girl what really happened as they have a happy life.