That's an interesting one there dice, I'm kind of coming back into the game after a bit of a sabbatical, so don't take any of this as define word...
If she's asking why she's doing it, she's just doubting herself, which lets you know she might not be gaming as hard as you think. She knows that you've got high value and she's assuming you have the answers. You obviously have something the man she's married to doesn't.
The good news is that she's just told you that she is at the point of LMR and ASD. I'd tell her you want to talk with her...give her a set date, and time, and tell her you're going to make it simple and to the point. Just get it out there. You find something very intriguing about who she is and she's worth some of your time.
Depending on how ballsy you feel like going, and if this fits her personality/the situation, you could go for something like this.
Tell her to put on a little bit of a disguise and meet you out one night where she could be legitimately away, sit down and talk about it. Have her meet at the hotel, so you can use the
David DeAngelo intro to a room (let her see the room, bring her in, then leave quickly, to help build her familiarity with the place) Then head to dinner. Once you get it to the point where she knows why you're there, and she knows why she's there you you can escalate and use freeze outs up in the room. Make sure she knows she can trust you though, it'll help prevent buyers remorse/guilt.
Again, these are just best thoughts and what I've read from the big books and other field/lay reports.
Best wishes bud