"You had a girlfriend," she points out, raising an eyebrow. "Which you kept telling me." Isabelle isn't that girl. She's free with her affections and she wasn't going to stop flirting because she doesn't know how to stop, but she wasn't going to go after someone else's boyfriend.

"Also, Alec kept telling me to stop making you uncomfortable." Alec is a fun ruiner, this is something Isabelle has known for a long time. He's less ridiculous since Magnus, but he still makes disapproving eyes at her every time she flirts in front of him.