No, polygamy isn't rape. THIS is rape.

[haele]

116. Depends on the point of reference and sub-group dynamics.

When I was doing Medieval recreation (SCA) back in the 1980's through 2000's, I knew quite a few polygamous groupings (in fact, I was invited to join two of them back in the 80's), and back in the old NewsGroup age of the internet, I came across a lot of long-term polygamous triads and "households" established back in the hippie days - mainly on the West Coast or out of Florida. (Apparently, a lot of retirees practice a type of "caretaker" polygamy where a younger couple or a widow or widower sets up a household with an married couple - primarily to help out.) Looking back, I knew of thirty cases of consensual polygamy over 25 years.
In not one of these relationships that I was aware of, was a spouse forced to have sex against his or her will.

As to "rape is common in polygamy, so you shouldn't accept polygamy", it's rather the same as saying (excuse me for being crude) "since poor messed-in-the-head sluts primarily use abortion as birth control, we shouldn't accept abortion".
Prior to the 1980's rape in a monogamous marriage was accepted, just as it was accepted practice that married women couldn't take out credit cards or have bank accounts in their own names - or use birth control without their husband's permission.
Polygamy is a codified relationship in the same class as Monogamy. Just, in this country, a polygamist relationship is typically centered around the legally married pair, with the satellite partners identified as dependents, "housemates", or very close friends.

And what about serial monogamists, who have their current wife/husband and their mistress/cicisbeo vying for who's going to be the next legal spouse when they get tired of the spouse they have? A man or woman who has been married three, four, five or more times - aren't they basically polygamists?

While there are fundy LDS and other cults that practice unwilling polygamy, child marriage, or strict patriarchal polygamy, it is still only the function of law that determines whether or not a spouse could be raped in those relationships and put a stop to it in those relationships. Just as it is a function of the law that will determine whether or not a spouse could be raped in a monogamous relationship.

I suspect that there's a lot of poly groupings around the US considering themselves "married" that don't get noticed by people who study that sort of relationship, because they aren't like the nasty fundy cultists who abuse their children and their women. And of course, no one likes to talk about the swingers, or spouse swappers, and that sub-group...

Haele