@Darudius
Yes he knows. In the War arc Ichika disguised herself as Miku and told him that Ichika was in love with him and that she would support them.
Indirectly, but after Fuu realized that it was Ichika in disguise later, but its still a confession.
He may have been hoping to discuss it further the next day when he chose Group E as he told her he thought that was the group she woukd choose. But she shut the door on him at that point saying everything was a lie and walked away.
They haven't had direct contact since and now she's quitting school and shut the door on him again today with his offer to private tutor and help her graduate with her sisters.