As for the people who were duped into thinking the unrequited yuri rival subplot will ever go anywhere in a het romance story, try and recognize the patterns. It's always introduced to add drama with no real consequences because despite the ensuing conflict, the straight girl will never be swayed. It's an annoying trope that shows up too much in romance plots (usually shoujo) and all it does is pad chapters so the authors can milk their story a bit longer. I've literally ranted about this.
That being said, this author is kind of a hack, so they might try to pull something out of their ass to turn the ending into yuri fap fuel for their fanbox. Or at least a fanservice chapter for the tankoubon.