i think it's near-impossible to find a man (and only slightly less impossible to find a woman) who will be satisfied with sexual exclusivity in a monogamous relationship for the rest of their life.
You might think that, but if their wife was genuinely like hey babe I'll allow you to have a one night stand with that hot lady over there, how many of them would say no?
Bad argument. You can be satisfied with current circumstances and still accept an alternative if it comes along. I can be satisfied with my Ford but I'm not gonna say no to A Tesla if it's offered.
For some men being monogamous is part of their identity, as they see it as necessary to being a good man and a good partner. So they can have urges but still want to remain faithful no matter what
Depends. If they knew the wife is perhaps testing their loyalty, many would say no. And if she was genuine about it, then what would be the point in monogamy in said relationship? This desire would probably be expressed early on.
First of all, MANY men would say no. So would many women.
Second of all, if there's expressed permission and encouragement for a one time indulgence, that still isn't breaking the definition of monogamy anymore than having a "cheat day" cancels the concept of a diet.