Easy? Don't statistics indicate marital infidelity is the norm? I would suggest that indicates "easy" is not the right word. Statistics aside, as a gay man observing my heterosexual peers, friends and business partners, it's my experience that straight men almost always cheat on their wives, maybe not regularly, but at least sometimes.

Also as a gay man, it's my experience that in my culture, relationships that are at least somewhat sexually open are ordinary. Lots of gay men don't expect strict sexual fidelity, and I believe that makes our pair-bonded relationships stronger and less riven by jealously and stress.