@thatno0b, answer is simple, he doesn't look the other girls as his gf(even Kazuhana he just has a crush on her and looks upto her), every girl in his group is just a friend to him and he doesn't want to make anyone in the group sad, remember that no-matter what the girls do to get close to him - he thinks they're teasing him and doesn't take it seriously, the only things he's serious about is his passion towards becoming fashion illustrator and helping his friends, these are all quality of a bland MC who doesn't have a clue about how people in his circle feel about him, tbh this also happens in real life but it's very rare that's all.