The plot literally revolves around making a female monster, as the titular Bride, for the existing male monster. You're stretching really hard to make mentioning sex in this context as sexist. Sex is plot relevant in this movie, again, called "The Bride", and they didn't say it was uninteresting because it was a female lead character. They mentioned many details that left them uninterested and none of it hinged on sexism. Chill out.