It's also good to remember that most ancient marriages were not about love or even sexual desire, but about wealth, sharing labor, safety of union and having kids. This is why most marriages were not negotiated by the couple alone, but by the families as unit. Sure love marriage was seen as good thing, all cultures had stories about love and its wonders, but ultimately love doesn't bring food, land, animals or other material goods and without those there is significant possibility that you will die, starve or otherwise end up suffering. So most marriages were fairly practical, how the couple felt about each other being just one factor among others. Sure if you can get the perfect couple go for it but if not okey marriage is better no safety net for future. Generally as long as the couple could get along well enough, it was good enough and you probably will grow found of someone you share you life and bed with anyway. So someone being gay probably wasn't seen as an much of an issue when everyone knows that marriage and love aren't the same thing. As long as he can perform to get the next generation, who cares if the husband has preference towards the dick.