Possible cheating fantasy threatening my relationship *trigger warning*

I don't think the real him would neither want it nor like it. While some - men and women alike - freely have sex without love, they tend to do so outside romantic relationships, not within them. Cheating and cuckold fantasies in pair bonded couples have little to do with pure sexual needs, but should rather be classified as a sign of mental instability. No sane person shit where they eat.