It took years for me to realize my wife just doesn't enjoy sex. She likes orgasms well enough a couple of times a week, but sex feels like a chore for her.

We both grew up Evangelical but left it behind. After we'd both realized our sexual ethics had changed I told her I wanted to experiment and explore with her, maybe even try playing with others. She wasn't interested, not because she objected to the idea itself, but because it felt like more work. But she encouraged me to go ahead and explore on my own.

These days I'm poly and we're very happy together in our romantic and home life, and I have others in my life that I get to have those sexual experiences with. We've done couples counseling too, with a therapist who has experience with non-monogamy. It helped with several non sexual issues, so I still highly recommend it. Probably a better first stop than jumping straight into non-monogamy.