"I don't want to," not right now - and not at all. If it's left up to him, he wants to stay, even if he's not sure how much he could take of it on his own. "If you're here... I'll stay."

There's a little more to it than that, though, isn't there? Like this wouldn't be just for his own benefit, but if Kai were to wake up to the both of them waiting for him... "I know that... Kai would be happy if you were here, too." The two people he loves, waiting for him to return to them, wouldn't that be an ideal way to come back?