First, apologies for getting off on a bit of a tangent on LadyLove's intro thread.
Yes, we're really dragging it off track because you felt you needed to bring up that gender stuff, since the wife is bi...
Another consideration about your premise is that, even a newly out bi wife, who wants poly so she can "explore her lesbian side" might get hit on by hundreds of more men than women, unless she looks for a new partner in strictly female only spaces.
Men are so aggressive. If a man knows you're poly, he doesn't care if you're bi, he just thinks, ooh a vagina for me to fuck. And he pursues that.
Women, by and large, even bi and lesbian women, often expect to be wooed and pursued. So, it's going to be much more work for a newly bi woman to find another bi or gay woman to be with. And meanwhile, men are going to be hitting on her. Even if she "goes poly" to get with other women, she might, along the way, end up with more offers from men that those elusive women.
I am speaking from personal experience. I had very little luck finding women on OK Cupid, but hundreds of men messaged me. Maybe even thousands.
And, Mags, you make good points - the whole idea of "ownership" does underlie the issue that most mono men have with "sharing" their wives - but, then again, the women have their's also - say, "hands off my man, bitch".
As a society we clearly have a mono indoctrination that often does manifest as an "ownership" mentality (for both sexes, it would seem - but, granted, more so on the male side).
My woman, my man. Yes. Women are men's sexbots. Women are trained to hide their sexuality. Men, to them, have been paychecks.
So, it's "Keep your hands off my sexbot." And, "Keep your hands off my paycheck."
Of course, this is changing, but it's going to take 1500 years to undo 3000 years of patriarchy. We've barely scratched the surface.
And that mentality undoubtedly underlies the notion that most "ordinary mono" men would be more comfortable with their wives having a girlfriend than a boyfriend. Of course, as you noted, it doesn't *really* mean that the men are "safer" that way, and I would be the first to agree that the wives might indeed have a much more satisfying relationship with another woman than another man, sexually and otherwise.
So, I'd ask that you reconsider even mentioning your theory to newbies, since it's just an illusion.
My wife's request that we open our marriage and transition to poly prompted me to dive into a fairly deep study and contemplation of polyamory and its relationship to monogamy. My key conclusion was that the belief that monogamy is the normal, natural, default mode for relationships is largely (perhaps even completely) due to cultural-religious conditioning. And that the conditioning can be "un-learned" with effort.
However, my real point - tying this back to a spouse who wants to open the marriage, but the spouse is reticent. It is not that one spouse "owns" the other and has the "right' to say, "Your body is mine and I will not allow you to share it". It is about having a contract with your spouse (via marriage) in which you have both agreed to be monogamous and have sex only with each other. And be in love only with each other.
To remain ethical, one cannot simply ignore the contract or declare it null and void at will, while expecting the other spouse to comply, remain married, and just say "ok, sure" - if they are not in agreement. One has to be prepared to attempt to renegotiate the contract in a way that works for both, or be prepared to walk away from the marriage (if they deem poly to be worth it). Or possibly just walk away from the idea of poly - and struggle on with the mono life.
But happily, if both agree - it is possible, with effort and lots of communication, for a mono couple to successfully make the transition to poly.
