Adam was just talking and teasing Leila when he suddenly felt some hostility directed towards him, like a sixth sense.
He turns his head to look at the table Cassie's friends are occupying and sees a young man looking at him with hostility. As soon as Adam makes eye contact with him, he turns his head away, clearly caught off guard by Adam's challenge.
Adam smirks. He doesn't know why this guy is suddenly showing hostility towards him, but seeing the girls in the friend group, he assumes that some girl in the group might have expressed her attraction towards him.
Adam is not wrong. But it's not the girls sitting around the table, but Cassie, who is the reason for the hostility being directed at him.
The guy clearly likes Cassie, so seeing her act all embarrassed and trying to calm her friends down and not to out her before Adam pissed him off.
