Oh, high school. Things seemed so big and important. And really, they were. When something is the most painful thing that has happened to you in your life, that is an intense pain even though people that are older will often scorn the experience.
So, in high school I had a friend and her girlfriend had cheated on her. Her girlfriend openly flirted with the guy I was dating (which startled me more than anything, I’ve never experienced jealousy as a thing). I was like a dog with a bone and couldn’t let it go. She *should* deal with this! She had to deal with this! How can one not deal with this?!? So, this built distance between us. And when the relationship ended I couldn’t be there to pour affection on her, because of the distance. It’s better, I think give an opinion but still be neutral, let people make of their own minds. That way you can be there for them.