Alec told himself that he was being selfish and melancholy. Jace had to make his own choices, even if they meant breaking a promise that he'd made to their family, to his parabatai. Getting angry would just hurt them both when Alec had known that the promise had been to good to be true. When he'd made it, Jace had had good intentions, but Alec knew the cavalier attitude that his parabatai had regarding his own well-being. He'd accepted that when they were kids. Being hurt by a trait that he'd understood years ago was foolish. Jace didn't mean to hurt them. He just didn't know how to deal with his emotions in a way that wasn't self-destructive.

He was so caught up in reminding himself not to be hurt that he didn't notice Jace moving until he was automatically scooting over to give his parabatai better access to the piano. Alec recognized the music, expected Jace to continue playing without any other accompaniment, but then his parabatai began to sing.

Watching his parabatai play, he tried to understand what was going on. It seemed obvious, but the obvious couldn't be true. Alec had waited years for some sign that Jace was interested... But that couldn't be right. Alec was married. Jace would never ruin that for him. He'd never ruin that for anyone. Jace had flirted and probably done more than that with his flings, but he'd never intentionally broken up a relationship. He wouldn't hurt Alec by ruining his happiness with Magnus.

Unsure of what to do, he let instinct take over, matching his parabati's motions, adding to the melody which was the only real answer he could give to the question he assumed was part of the song.