Part of what made the original Frozen such a hit with fans was the way in which it upended familiar Disney tropes. Ideas of nearly instantaneous "true love" were questioned and romance was never the primary goal for the princess main characters. The film was a breathe of fresh air in the Disney canon.
Having said that, following the first film, and the announcement of a sequel, there was a groundswell of support for the idea of giving Queen Elsa a love interest in the next movie. The twist being that these fans were hoping to see Elsa come out as the first gay Disney Princess. That did not happen, and Frozen II writer and co-director Jennifer Lee recently told Screen Daily that, while there are no limitations on the kind of character that can be featured in a Disney movie, that just wasn't where they wanted to focus with Frozen II. According to Lee...
We can do any kind of character, but with Elsa we were really looking at where she is in her life and the pressure she feels carrying the weight of the world. We weren’t focusing on romantic love.
Rather than take Frozen in an entirely new direction, the sequel tries to follow on the themes of the first film and deal with Elsa's place in the world. In the first movie, she comes to terms with who she is, and in the sequel, she wants to understand why she is.
Certainly, it's hard to argue that any attempt to deal with Elsa's romantic life at the same time would have required juggling a lot of story and, especially if the movie had gone for it and given Elsa a same-sex relationship, it likely would not have been given the attention such a decision deserves.
The first Frozen made Anna's relationship a subplot and that continues through to Frozen II, but Elsa's story has yet to deal with romance in any way. On the one hand, that's a welcome change of pace from the Disney Princess that finds coupling up to be their main goal in life.
The song "Let it Go," in addition to become a massive hit, became something of a coming out anthem, and Frozen II's "Show Yourself" is hitting many of the same notes, as both songs deal with accepting and understanding one's self.
On the plus side, Frozen II continued to not deal with Elsa's romantic interests at all, and in doing so still leaves the door open to what these fans are hoping for. Maybe we'll get a Frozen III that will answer the question, or maybe it will just be left open to interpretation, even that much is something of a shift for Disney.
It feels like, eventually, this step will be taken and we'll meet a gay Disney heroine. It may not be Elsa, but if nothing else, Elsa has shown how many people would like to see this, and may have played her own part in one day making it happen.