Oka is fucking evil.

Banri treating Linda differently is eons away from Linda treating Banri differently. Banri did not even know they were acquainted, and he had no choice in ANY of his interactions. I think he was being way too strict when he judged himself negatively for his actions.

Linda on the other hand, knows everything. She clearly had a choice to reveal herself or not, but chose the latter because of her guilt. Imagine knowing someone is acting in front of you intentionally for an unknown reason. That is how Banri feels right now, at least before Linda confessed her feelings.