I think part of my issue is that I'm not really polyamorous in a sense. I am in a marriage with someone I love deeply and have a wonderful life with, but I'm not sexually attracted to him nor do I have romantic feelings for him. I laugh when I think of having more partners! I can't barely stand one!
What I am after is the French-ish notion of a lover. Someone who I feel passion sexuality, and yes, longing for. Since I want to avoid domesticity at all costs and longing is a huge key in "being in love" for me, I tend to fall for men who are somewhat unavailable - i.e. cheating, or young, or live across country. I have put a lot of thought into whether I could have all these feelings in one person , i.e. my husband or a different husband. I don't know. I don't have the answer.
However falling in love with someone cheating was pretty awful. Because of my disability, my therapist argued that being a secret was the worst thing humanly possible for me. I, myself, hated being lied to. My friend drove me to do a lot unwholesome behaviors - lie myself and so on. Mostly, it was just painful to love someone who was suffering so much. This was largely an emotional affair, not sexual.