I’m thinking that maybe, partly, Kaneki also cried because of how much he realized Touka’s everything belongs to him at the moment. And how much love he felt because Touka is giving her all to make him happy.
Just go back to Ch122 when he said, “Shouldn’t she treasure it?” Talked about having sex/making love.
And then in one of the panels where in he realized Touka is also a virgin. JUST HOW LOVED YOU ARE, BOY, TOUKA DIDN’T GIVE HER FIRST TIME AWAY TO ANY GUY IN YEARS BUT WHEN YOU FINALLY CAME HOME SHE IS ALL PREPARED TO GIVE HERSELF. IT MEANS SHE REALLY THINKS THAT ALL OF HER BELONGS TO KANEKI. AND KANEKI REALIZES IT WHEN SHE SMILED AT HIM.
Oho~ I AM SO HAPPY I CAN FINALLY SLEEP IN PEACE FOR THE FANDOM.