Did Muhammad connive Zainab and Zaid to divorce?
Had Prophet Muhammad engaged in any unbecoming behavior, no shortage of critics existed during his lifetime. Likewise, Zainab was Prophet Muhammad’s cousin and he had ample opportunity to marry her before her marriage to Zaid was even a nascent possibility. It is baseless to allege that his infatuation for Zainab somehow spontaneously emerged only after her marriage.
While not a single critic of Prophet Muhammad’s time attributed to him any wrongdoing, contemporary critics somehow find an opportunity to do so. To silence those critics, Christian scholar Reverend Boswell Smith writes:
“It should be remembered, however, that most of Mohammed’s marriages may be explained, at least, as much by his pity for the forlorn condition of the persons concerned, as by other motives. They were almost all of them widows who were not remarkable for either their beauty or their wealth, but quite the reverse. May not this fact, and his undoubted faithfulness to Khadija till her dying day, and till he himself was fifty years of age, give us additional ground to hope that calumny or misconception has been at work in the story of Zeinab?” 
Critics during Prophet Muhammad’s time and contemporary scholars both agree that Prophet Muhammad committed no wrong.
 Reverend Boswell Smith, Mohammed and Mohammedanism, page 89 (London, 1874).