If he only wants to have threesomes with another woman and only go to female strip clubs and only have a "sister wife" added to your relationship.... That's not polygamy.
That's polygyny.
In polygamy you'd have equal opportunity to go have threesomes with another man, have another man as your second partner in the home, and he'd go to male strip shows with you
So, he doesn't want polygamy. He doesn't want anything "equal".
He wants to have sex with other women while losing none of the benefits of marriage etc with his wife.
Also ... Threesomes - with other women - you're presumably heterosexual, not bi or lesbian - so what are you supposed to getting out of the threesomes??
Why are you supposed to be comfortable with them?
I can appreciate a beautiful female but I'm not sexually attracted to females, I'm heterosexual - not lesbian or bi - so why the fuck would I want to have sexual contact with another female?!
(That's totally aside from the issues of watching my husband have sexual contact with another female).
Really he just wants permission and agreement to cheat, to have sex with multiple women, and to do so without losing anything.
None of this is remotely normal incidentally. Hrs gax lighting you trying to pretend it is.
Very few people are polygamous.... Not that this is polygamy he wants, anyway.