Possibly not in that specific product, but, certainly over the range of products it would be no problem. And besides, WOTC doesn't make one shot adventures. How many married or in relationship NPC's are there in Out of the Abyss? I have no idea, I don't have the module. And the Adventurers League version does cover several modules. Heck, let's take a peek at Harried in Hillsfar. Five one shot modules.
Very first adventure you have a married couple that adopts children. Now, they also have children of their own (born after the adoptions), so, it does make sense that this is a hetero couple. But, since the couple don't actually NEED sextuplet children for this adventure to work, this could easily be a same sex couple. The monstrous births that come later (sextuplet demonic goats) and the confirmation from another NPC about the bizarre births in the area, means that the couple don't actually need to have children for this adventure to work.
Adventure two features a half elf girl whose parents are not present. Funnily enough, when you do meet the parents, they are both half-elves. Avoids the problem nicely. But, again, you could make the parents same sex and the girl adopted without any problem whatsoever. Granted, the parents in the adventure are ... well, I don't want to spoil it, but, it is possible that they could have adopted the girl.
The third adventure features two couples, the first of which features a pregnant wife who is traveling to a holy site for blessing for the child. Ok, fair enough, that might be a bit tricky to change there.

But the second couple are priests of Mieliki that the party meets after the priest's companions had been killed. Easily possible to change the gender of one of the priests. Although, this one would run into some of the complaints from above. But, not a huge deal.
The fourth adventure features no couples at all.
There are no couples in the fifth adventure.
So, in the first three adventures, a minor change to any one of them would add a same-sex couple to the series. No one is asking for all of them to be changed, that would be ludicrous. But, again, would anyone have a major issue if one of them were? Certainly that first adventure would work easily just as well with a same-sex couple as a hetero one. It wouldn't make the slightest difference to the adventure and it would go a long way towards paying more than lip service to inclusiveness.