I don't think that tolerating bad behaviour reflects negatively on anyone's character. I'm sorry if that was implied, it wasn't my intention.
My comment was intended to take the focus off the other person entirely. You can't control what they do, or who they are, so why bother trying to decipher if they are good or bad or anything in between. The only thing that matters is your response and being okay with what that says about you. If you can accept them and counsel them despite their values which clearly don't align with yours, that says a lot about your character in a positive way. It shows strength and forgiveness and tolerance. But do I also think it requires some mental gymnastics? Yes, I do.
I saw a close friend's profile recently on Tinder. He has a partner, a one year old, and a newborn baby. I don't know what my response should be in accordance with my values, so I haven't acted yet. But I would hope I'd show understanding at least, even if my decision was to end the friendship. I've certainly performed mental gymastics to explain and excuse it: he might have an open relationship, it's just harmless looking, maybe it's a fake profile with his photos. I can tell myself this, but my gut knows I am wrong. And my character won't let me sit comfortably with that.
These things ARE complicated. But I do believe in objective principles of right and wrong, and dislike the trend away from objective morality.
I'm sorry if my comments were too personal, May. You clearly trust your gut, and are sitting comfortably with that, which is all that matters.