This is based off of a scene in the game that you can see (as far as I recall) only if you have Riesz among your selected three characters and don't have Hawkeye among them.
Actually, I'm pretty sure this is what happens at the end of the Rolante segment, so long as you have Hawk in your party but not Riesz. Otherwise, if Hawkeye weren't in your party, he would not be there at all.
I'm pretty sure you come across Hawkeye near the beginning of the Rolante segment when he's not in your team, telling you about the curse on Jessica and not to kill Bigieu. Riesz complies if she's in your team, getting the kiss from Hawkeye out of gratitude. Maybe there's something different (or similar, just happening at a different point) if you have Hawkeye and not Riesz as you're referring to. I haven't really played many games of SD3 without Riesz, so it wouldn't be surprising if I haven't ever came across it that way yet.