It'd be useful if someone had another power that forced people to go yandere for you and you were invulnerable to that. Also you could threaten to inflict it on other people, if you were into getting things through threats, and if they wanted to stay loveable they'd have to give in to your demands. Oh, and you could protect people from stalkers and shit. Of course it's a lot more useful if you can control how long the effects last, and not as desirable if it's always permanent.
But since that stuff doesn't come up often, it's a pretty shit hand.