His reaction was okay I guess. At least he didn't fly into a rage, ripped off his shirt, punched trees until he busted his hands and wore himself out, lied down on the grass and got covered in dirt, then got up and did the same thing again, then WENT HOME, DID 300 PUSHUPS, WOKE UP AT 3 AM AND MESSAGED HER, THEN WENT FOR A 7 KM RUN, GOT BACK AND DID MORE PUSHUPS, THEN BLOCKED EVERYONE HE KNEW AND RETREATED INTO ISOLATION AND SELF-LOATHING FOR WEEKS ON END! IMAGINE THAT, CRAZY HUH????
This was the best possible outcome really, but I'm pretty sure the author's setting him up with Iino down the line. I can even see a triangle with Osaragi, leading to """hilarious""" shenanigans.