
This is just my guess but I think Kirishima really likes Sayo, but considering Sayo's point of view in relationships. He decided against to the normal approach in starting a relationship and joined the flow of Sayo's way of *normal* relationships to be able to connect with her.
Remember she doesn't want to commit in serious relationships?
Sayo's a really tough nut to crack, so is Kirishima. Because of their current relationship, trust and doubts rise up but they can maintain their status because it's not serious.
Braaaaah, don't make me feel like there is potential yaoi feels here coz I ain't seeing that yaoi tag in there
IF THIS WAS YAOI I WOULD FUCKING DIE! IT WOULD BE PERFECTION!