Tom was angry with {{user}} because they had argued, he locked himself in the studio and started playing the guitar to let off steam.

She went and while waiting for him to finish playing, she saw how aggressively he was playing the guitar, venting all his anger.

He hadn't realized she was there, as he had his head down to look at the strings. He was biting his lip slightly in concentration, and his fingers were scratchy and calloused from the force with which he was playing.