Certainly Jenny has the right to abandon her life and hitchhike around Mexico, and her husband doesn't control her. However, in a partnership of marriage, there's usually a little more cooperation going on where one party does not run off to another country to hitchhike around while the other party is worried sick back at home.
There is something off about this missing person story.
I think it 's just a certain kind of free-spirited youthfulness, the same spirit that probably led her to want to marry an American so she could move to the US. I've spent time in hostels in my travels and they're full of young people who are unwilling to settle down to the corporate grind and boredom of middle-class life.