Jay had been probing Matthew for hints regarding where she thought was a good place to start looking when it came to Olivia. She knew that the girl said she was over Peter, but after a few drunken conversations, she realized that Olivia was anything but.
It was extremely plausible that Olivia voluntarily left with Peter, and he and Bastien had gotten into a fight over it. Among men, it was not uncommon for the loser of a fight to exaggerate his enemy's skill in an attempt to make himself seem helpless.
If Peter and Bastien fought over a drunken Olivia, Jay was almost positive that Peter would have more to lose in the situation and would therefore behave more aggressively.
Matthew's statement about Peter being an idiot was all Jay needed to confirm her own suspicions. She had met Bastien once, and she knew the man was fond of Olivia, and for Peter, Olivia would make the perfect bargaining chip.
