'Like us' definitely made the complicated nature of the question much more clear, but also puts a strange kind of angle on it that Shinji wasn't entirely expecting. Would Kai even be asking this if it weren't a personal question? Would those flowers get coughed up if he were asking on someone else's behalf? It certainly doesn't have anything to do with Kyoko's secret, he figures, given how adamant Kai had been about keeping his lips sealed on that, so... what's with this question now?

A small seed of worry sprouts in his stomach, but until he finds out more about this particular wonder of Kai's, there's no reason to panic. Not yet.

"So... if you or I," hypothetically(?), "fell in love with another person?"

Is that what we're going for here?