Hi Nunalto! Awww! I'm sorry Polar's route was...well..."polarizing". lol
Tbh, yes his route is probably one if, if not the most melancholy one. In terms of the endings themselves...there is no definitive document stating what happens in each. But I can tell you that there are 11 endings in total.
With most, if not all, of the LI's having a "best" and "good/OK" ending. There are bad ends, friendships ends as well as a funny joke ending. I hope you find one that pleases you more than the Polar one. =)