>>38877233Either your new or baiting for something, but I'll give you an answer anyway.
>polygyny and/or lesbian couples are culturally accepted in equestriaYes, they're called herds Anon, and would be very much accepted in RGR society do too the ratio of mares to stallions being 7-1 I believe. Also, there are no lesbian couples in Equestria, just pseudo herds (stallionless herds) where mares are in a relationship with other mares, but are still on the look out for mister right to come along.
>are mares expected to be bisexual?Still going off the herd concept no. Even if there's a lack of dick to go around mares still have a choice, even if there are other mares in the relationship they aren't expected to go down on other mares if they don't want to.
>how would RGR effect this?Not at all, in fact, it's part of the reason this thread exists in the first place Anon.