The Silver Wolf - Alice Borchardt
My first warning should probably have been that the author is Anne Rice's sister, but despite that I still went ahead with the swap...

Our protagonist is Regeane, a woman from a noble family around the time of the fall of the Roman Empire - effectively held captive by her uncle and cousin, who both fear and hate her because she is a shapechanger (able to take the form of a wolf, if you hadn't guessed from the title), her only protection is the fact she has been promised in marriage to a mercenary nobleman. Unable to always control her abilities, Regeane fears her upcoming wedding but knows that it is her only chance to escape from her relatives, so she agrees to go along with their plot to murder her future husband once she's married.

And that would probably be fine if that was the only plot and Borchardt had managed to get herself an editor. Instead of which, the storyline meanders around a couple of subplots involving a high-price courtesan and her relationship with the pope of the time, not to mention bringing in other supporting characters (who will probably crop up again later, I expect). The writing is verbose to say the least, not helped by the author's tendency to refer to 'the wolf' and 'the woman' as if they're two different people. The series continues in Night of the Wolf.