... I don't get what's so interesting, fun, funny or even how it's logical to have a stalking horse say they're the main character's love rival, after the main character is already in a relationship... I mean, leaving aside all the icky implications of treating someone as a trophy to compete over, isn't that just being a stalker?
Also as a yuri fan, I really hate seeing gay girls thrown in as cheap "rivals" in these stories, then "straightening" them at the end, like Char in Kishuku Gakko no Juliet