Earlier today Nintendo confirmed Fire Emblem Fates will feature same-sex marriage.
"[Fire Emblem Fates] includes the possibility for a same-sex marriage to take place between the main character created by the gamer and another character in the game."
"In the Conquest edition of the game, there is a male character that the game's player may have his/her male main character marry after they bond in battle. Similarly, the Birthright edition features a female character that a female main character may marry after bonding in battle. Both of the aforementioned characters can be encountered in the third edition of the game."
It's nice to see Nintendo giving us more options in Fire Emblem Fates. Nintendo had this to say supporting diversity in their communities.
"We believe that our gameplay experiences should reflect the diversity of the communities in which we operate and, at the same time, we will always design the game specifications of each title by considering a variety of factors, such as the game’s scenario and the nature of the game play. In the end of course, the game should be fun to play. We feel that Fire Emblem Fates is indeed enjoyable to play and we hope fans like the game."