I carry some guilt myself. For years I was letting my wife down somehow. Surely there was something more I could do to make her happier.
Eventually I accepted what she was telling me. She was getting plenty of attention from me and she didn't need anything else. I wasn't depriving her by giving my attention elsewhere.
It took a LONG time to sink in though. Well over a decade, and I'm still not 100% convinced!
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