Can’t say my situation is the same, been fairly disenfranchised by monogamy for some time... it just never felt natural to simply love one person forever and ever and feel nothing for anyone else ever again. I love my SO and I’ve broached an open marriage but it was rejected out of hand after various conversations and including therapy which got us nowhere. Sex also became an issue over time, and now I have an AP who I really like and is fun... but I am kinda sad that I can’t share that happiness with my SO, it’s not guilt, it’s just disappointing... so instead I compartmentalize the 2 aspects completely as separate lives. It helps that my AP is suuuuuuuper relaxed about things so it makes it easy.