I think I'm in the voluntarily camp.
It bothers me that the husband used the find my iphone feature to find his wife's phone. Having been in relationships with controlling men, it comes off as disturbing to me. It sounds like a very controlling move, one he possibly used in the past to keep tabs on her. She may have just decided to leave a bad situation.
At the time I had a significant other who thought it was appropriate to be tracking the gps on my phone, he also had keylogging software installed on my computer, and my phone and the internet modem would be taken with him when I was left at home alone. I wasn't "allowed" to go many places, even to visit my mother at her house. I didn't have a vehicle, but I did fantasize about just driving somewhere and leaving my phone and getting the hell away without telling a soul where I was going. No one on the outside had a clue any of it was going on.