From The Sultans, by Noel Barber (Simon & Schuster, 1973), pp. 70-71:
Most Turks at this time seem to have been reasonably happy with one wife, perhaps because the dowry was given by the bridegroom, or because divorce in those days was easy — understandably so, since many boys married at thirteen or fourteen to girls of eleven and twelve whom they never saw before the nuptials.
But easy divorce had several curious consequences. A man could not marry a divorced woman until she had been divorced from her husband for four and a half months. If a man divorced his wife twice, he could take her back. But if, as sometimes happened after marital tiffs, he divorced her a third time, and then realised he still loved her, she could not return to him until she had been married to someone else. This was meant as a check against abusing easy divorce but it soon produced a professional intermediary willing to marry the lady for one night. He was usually old, paid for his services, and expected not to be over-enthusiastic in the performance of his duties.
Divorces — often followed by remarriage — were common among one class in Constantinople: the men who did have one or more concubines. Inevitably this led to friction, scenes of jealousy, and often physical violence, particularly if the wife felt that she was being cheated of her marital rights, for though the husband could call for his concubines six nights a week every Friday was strictly reserved for his wife.