How do people enjoy love triangles?

I hate love triangles in general.

The feeling of rooting for a character when it's clearly obvious that they are just going to be a plot point for the main characters makes me extremely depressed.

Even if I'm not rooting for the 2nd lead, it still makes me sad knowing that this character that I have read 50 chapters about has strong feelings for the mc and has this sad backstory and how the mc has changed him etc. will just be left alone in the end.

Love triangles make me depressed because I spend so much time on these 3 characters but I know that only 2 will get a happy ending.