Probably forever, but Yuya won't say that. The Fae are long lived, however, and obviously no strangers to holding grudges.

But he doesn't want to make Gon worry more about the potential danger they've specifically landed themselves into. Yuya just nods, his hand almost grasping Gongenzaka's in an absent reflex. "Yeah. We have to remember making it home."

So... he's got to tame his impulses just a little. That's fine--he wants nothing more than to go home, too, and be with all his friends and family. At least there's one less person he has to be worried about losing their lives or freedom to the carnival. Or sanity.