fwiw, T uses me to complain about her other relationships. She's secure enough in me to know it won't push me away. I'm not sure that I like hearing about it all the time, and contrary to what you're hearing, her's is always, "I don't hear from them often enough" or "they did something that hurt my feelings" as opposed to "I need more love from them."
Still, what gets me through it is understanding that I'd rather her come to me with intimate details of her life, than not. Maybe one day if the passion dies it will cause issues, but for now, I get both, and that's good for the long run.... I think.
Me: 39 straight male in a V with
Wife: Kay - mono female - married 17 years
LDR girlfriend: Susan - poly female - 3 year relationship
Stakes - very intimate friend