I've read the book so won't include any spoilers, but I think the reason for the 'spook' thing is actually she knows nothing about him except what she's made up in her head. She married young and had a daughter in her early 20s - her own daughter said "You did this five years before me". I got the impression that she is treating this new guy like she would have treated a boyfriend when she was an adolescent, where she makes up things about him and succumbs to passion without thinking of consequences. He's already told her two different careers he's in and she's so giddy she's heard him but not listened. Also, because he was in the room with all those important people, she assumes he's like that himself, doesn't she?
With her husband, too, she's seeing what she wants to see. I did find it odd, though, that his student (smashing bottles) was outside the house in the middle of the night, then he took her home, only returning at lunch time the next day. I can't believe he would stay out all that time without being questioned.