I am still totally surprised about her going away for the weekend. I don't know if this was a test, or because he asked her and she was swept off her feet (didn't want to say no to "ruin" a good thing), or if she wanted to truly have a good time with him.
In my opinion, it was a HUGE test, and she was basically looking for your "permission" for her to have an affair -- a control thing, whereby she was testing you and saying "I can do this, and you can't stop me."