This is actually something to think about. I feel the most effected in such marriages are the first wives, who feel like they have total control over the husband. But here the thing to take into mind was the period in which it happened.
If taking the 1500's into consideration, that time it was a norm to have more than one wife. Rather a monarch with just a single wife was hardly found. In such a society I think women were used to being put in situations where there was not just one wife. So it is possible that they could have been friends. But I think the possible situation where wives could be friends:--> When one of the wives doesn't want the attention of the husband--> When the husband is hardly in townBut its definitely something to think about! 😕😕