Many years ago, I asked Jonathan Tweet through the Everway listserv (I believe this was the "oracle.wizards.com" one of ancient times) about Everwayans' attitudes toward homosexuality and lesbianism.
Here is a bit of his response to the list, with a scenario seed:
There's real pressure on Everwayan women to bear heirs (daughters). In a patrilineal society, one son can have a lot of kids by wearing out his first wife and moving on to a second (and maybe a third). In a polygynous society a male heir can have lots of kids by having multiple wives simultaneously. A son's breeding potential means that some of the pressure can come off some of the other sons. In Europe, for example, it was common for younger brothers (especially gay ones?) to enter the clergy.
In Everway, where an heir has to produce heirs with her own body, an heir's maximum capacity is limited. Even younger sisters, therefore, are expected to contribute to the next generation's population. Given this pressure, an Everwayan woman (especially an eldest daughter) gets grief for pursuing anything that kept her from having children, whether that interest is women or collecting butterflies. That said, a woman who bears children can get away with a lot on the side.
(All of which suggests a plot element: An Everwayan woman, perhaps an eldest daughter of a prominent family, has been declared infertile, freeing her of her breeding obligations. Now she's free to pursue her romance with another woman. But rumors suggest that the infertility exam was "fixed." Maybe she used magic to ask her fertility. Maybe the examiner was bribed, or sympathetic to the woman's desire to get out of her obligations.)
Men, on the other hand, are more like free radicals. Unless a mother is planning to marry a son off to a prominent family and gain some clout thereby, her son's pursuits and interests aren't that important to the family. Since a father is hardly even seen as related to his wife's children, even a married man could forsake his matrimonial duties and let his wife find another man to fertilize her.
Of course, marriages between men and between women would make no sense to an Everwayan. In the case of two men, what family would they belong to? None. In the case of two women, what family would they belong to? Both? Marriage is something that families do, not just individuals [emphasis added], so there's no place for gay marriage in Everwayan society.
Consider that 10+ years ago when he was asked this question, Jonathan Tweet could have simply ignored it. There was much less pressure for representation of LGBT people and relationships in gaming back then. He took the time to think his answers through, in the context of the culture he had created.
Even today, game designers sometimes do far less. I was struck by the "Lustful" Mental Flaw in Leagues of Adventure (2012) when I was reading the game rules last night. The Flaw is all about "the opposite sex". Perhaps a small detail, but these exclusionary frameworks really need to change.