Also in the manga, when Arima tells Yukino all about his past, culminating with him telling her that he loves her.
Another small, but telling, moment comes early on. Arima has confessed his feelings to Yukino, but she is beating herself up about her inability to respond to him. She finds a way to tell him during a student council meeting by just reaching down and grasping his hand into hers.
Yin and Yang album. Tsubasa. That is all.
When Maho and Tsubasa start to like Yukino and even become her friends. Dawwww.