A recent book,
For the Glory of God:
How Monotheism Led to Reformations, Science, Witch-Hunts, and the End of Slavery
Rodney Stark, 2004, says that Zwingli secretly married his wife while a priest, and subsequently married her publicly after embracing the Reformation.
For the Glory of God: How Monotheism ... - Google Book Search
p. 92-93
On page 92 it says he had affairs before marrying his wife, all while a Catholic priest.