You know you're screwed when you have to hide behind a yandere to escape a yandere.
I'm.....going to go over here.
::hides in front of Mama Raikou::
But yanderes are the best counter to yanderes. (Aside from, you know, a full SWAT team provided they are "just" human yanderes and not ones with superpowers, or whatever elite anti-super government agency exists if they do.) Although not usually mentioned, yanderes have essentially the same powers as slashers from horror movies in that they can teleport to always be behind someone, bypass ordinary means of keeping people out, and instantly render people less important than them in the plot completely helpless no matter how much more competent they are demonstrated, or at least claimed, to be elsewhere. (I.E. Superheroes being effortlessly knocked unconscious from within their own secret lair so that they can be strapped up to an overly-elaborate death trap in spite of being able to handle hundreds of goons otherwise.)
Besides, when you let the yanderes whittle their numbers down until there Can Be Only One, you can just say it was fate that helped the survivor win to be with you forever... or take advantage of her being worn down and injured to finish the survivor off as well if you're a total bastard and/or the winner was likely to be violent towards you, as well.