Alabama law does not designate any age wherein a child can choose where he or she lives. The court is always bound by the best interests of the child when it determines who is going to have custody. If your friend has not hired an attorney to represent him in his divorce, he needs to do so an soon as possible.
I was reading your question and can not speak for Alabama law, but do agree that relying on a child's decision is NOT the way your friend should bank. Hire an attorney.
Attorney Williams practices FAMILY LAW throughout the State of California and may be reached at (831) 233-3558 and offers free consultations. The response provided in this forum is not intended to create an attorney-client relationship. The information offered in this response is for general informational purposes only and should not be relied upon without further consultation with a legal professional after all relevant facts are disclosed and considered. DANIEL S. WILLIAMS, ESQ. LAW OFFICES OF DANIEL S. WILLIAMS 500 LIGHTHOUSE AVENUE, STE. A MONTEREY, CA 93940 (831) 233-3558 -- OFFICE (831) 233-3560 -- FAX