Kuroto's words to Senshiro in episode 19 "I always thought I was fine on my own. Living on my own and fighting on my own, I even thought eventually I would die on my own.But, I don't mind being with you.We're supposed to share, right?"
Senshiro's response is really sweet as well "I finally got to see it. Your smile."
Basically every interaction between Hotsuma and Shuusei that is not a Tear Jerker. The way they take care of, worry about and support each other is just really sweet.