Link with the Female Protagonist.
In the second movie he ogles Mitsuru's swimsuit, but otherwise never shows interest in her.
She loosens up later in the story and her social link indicates that the attitude is in part fueled simply by awkwardness.
It's then when Yukari points out how selfish her reasons for fighting are, especially since she had previously said she wanted to atone for the sins of the Kirijo Group.
She also refers to Ken and Shinjiro by first name during and after the October 4th clusterfuck.
Each is affiliated with one of the twelve.
She literally needs to explain to him that he's in love with her when he can't quite figure out why it feels different hanging out around her.