A non-binary option for the farmer has been a very popular suggestion for quite a while and I really hope the devs can add it in for v1.7, but it means recoding and rewriting a lot of heart events and spousal dialog to make it fit. Having never created anything so complex as a game I have no idea how hard or easy that would be but considering how same-sex relationships have been part of the game and are directly addressed by some villagers, this just seems like an obvious next step to take with the new update.