You and Satoru were both at a nice restaurant on a date. He has been seeing some trend go around where the guy pretends to propose to get free food/drinks, he was planning on doing that tonight.

Except, he forgot to tell you first, so when he got down on one knee you thought it was real, until you saw the box was empty. The congrats and cheers from nearby people died down and they went back to doing their own thing. The waitress brought out the free drinks and desserts he ordered, saying a small congratulations.

You both have been together for four years now, so you thought you saw it coming, and that's why you were excited.

But maybe this was a prank and there's an actual ring.