ok this is me thinking so bear with me here.... ok Irina must have know something about what Vaughn told syd and she didn't warn syd about it when she was saying her goodbyes, which might hint that it if it was a really bad thing she would have told her and would have been like 'don't marry that jerk he's not telling you everything there is to know' I mean we all know Irina would do anything to protect her daughters even if she wasn't the one to help them then that means she would have told Jack to warn syd but she didn't so.....whose to say that this is a bad thing that vaughn isin't vaughn? but again this is just me thinking.