> to make your point you have to show that it's better for women when men actively try to seduce each other's wives at every opportunity
Not really. The point actually should read "men making an agreement not to flirt with married women would be worse for married women as a whole".
Note this differs from your version in two important ways:
A1. The group that is benefited is not women, but married women
A2. "Every opportunity" is replaced with "where the man in question believes it is a good idea"
And the version with those modifications is clearly true.
High level argument:
B1. the cost to happily married women isn't particularly high (they stay in their relationship, feel flattered, have a fun conversation, etc)
B2. the cost to unhappily married women would be particularly high (since they have less knowledge about potential alternatives / may stay in a bad situation longer due to lack of information)
I'm not sure what the exact population sizes are for those two groups, but by using the divorce rate as a quick proxy we can see it's a high enough ratio to be net positive. Hence it would be better.
(If you are thinking about talking about obnoxious flirting, I will point you to A2 above)
FWIW "Please explain why women get remarried" is just a shorter version of the above argument -- the reason men not flirting with married women is bad for married women as a whole is because some would get remarried.
> If we take this logic even further, perhaps ever-more-clever ways of men sabotaging the others' relationships with their wives would have even BETTER results for the wives, because they are more "competitive"? Doesn't this have diminishing returns?
You talk about straw men in other threads. Do you really not see the straw man in your last two replies to me? No one is arguing that Apple should seek to harm the way that Google's employees feel about Google except in true ways ("Google is paying you 20% less than market" is good if true in much the same way as "Greg is cheating on you" is good if true. Both are of course bad if false)