I had a partner for eight years. We met when we were both 31. She was my first monogamous relationship theretofore because I decided to give monogamy a try. She was utterly, screamingly boring in bed. There was nothing else notably wrong with the relationship, except for her unwillingness to communicate on anything beyond household, workaday topics. No oral (give or receive), no anal, not into foreplay, and she would just lay there. But no conflicts either. There was the advantage of she was always willing and ready to go without any foreplay or lube. She got off and claimed she was absolutely sexually satisfied. Sex wasn't even fun in the context of Free Use, which is a kink I enjoy. I tried to engage her in all kinds of Gottman Method relationship work, but she bluntly and explicitly refused.
At one point early in our relationship, she moved and clamped her vagina in a way that was quite enjoyable. "Honey, that was great! Please do that more." And for the rest of our relationship, any such complement was a sure-fire way to make sure it would never happen again. After eight years of nearly daily, invariably terrible sex, I stopped approaching her sex for three weeks. She never said a thing. On day 22, I broke up with her, and she was absolutely gobsmacked, claimed that I was throwing away eight years of great history. She hadn't even noticed that there had been no sex for three weeks.