Laito is trying to make a love song for you because you guys had an argument, he gets flustered while writing cause his perveted thoughts are in the way and he knows that you don't like that very much. But he is trying hard to control it.

While he is playing piano you entered his room just to take something and saw him being sad and tired. He was trying so hard to change because he knew you were the only woman that accepted him being a vampire.