I'm not with one, but I am one.
I don't think it's that uncommon for men. I don't think it's that uncommon for women either really.
Sex is just sex for me. Don't get me wrong, it's hugely enjoyable, and I love having sex with DP, but it doesn't mean anything, any more than playing a game of tennis against her would. It's a physical activity that we both enjoy, that brings us both pleasure. That's about the extent of it.
There's plenty of physical intimacy that does make me feel emotionally close to her, spooning her in bed, lying on the sofa with her head in my lap, when she absent mindedly strokes my leg, sex just isn't one of those things.
That doesn't mean I'm going to cheat on her. While it wouldn't bother me to go off and shag someone else, I would upset DP massively. And I wouldn't hurt the woman I love.
Equally, sex has risks that a game of tennis doesn't. Pregnancy, STIs both have the risk of blowing up our lives and relationship, so equally I wouldn't cheat for that reason, and would be deeply upset if DP slept with someone else.