Oh, I hate it. I don't play dating sims to feel like I am competing for someone, especially when this rival does nothing to earn their affection but we are expected to break our backs or sacrifice our newborn for a speck of affection. This and the dead wife trope are probably my least favorite.
I also hate it when when the people in charge are very obviously ship the characters with each other and not with MC, so they pair them up together if MC is not involved (I am looking at you, Arcana).
There's been a single instance when I was okay with RO having interest in another RO, but the writing of this game was immaculate, so MC didn't feel like an afterthought because they were interconnected with everyone and pivotal to the story. The game is Fallen Hero btw, it's not an otome, but an interactive "choose your own adventure" text game.