Sharon Shinn 
Shape of Desire [EPUB ebook] 

For fifteen years, Maria Devane has been desperately, passionately in love with Dante Romano. But Maria knows that Dante can never give everything of himself back — at least not all the time. Every month, Dante shifts shape, becoming a wild animal. He can’t choose when he shifts, the transition is often abrupt, and as he gets older the time he spends in human form is gradually decreasing.Maria has kept his secret since the beginning, knowing that their love is worth the danger. But when a string of brutal attacks occurs in local parks while Dante is in animal form, Maria is forced to consider whether the lies she’s been telling about her life have turned into lies she’s telling herself . . .