Knock Out (Worth the Fight #1) by Michele Mannon

Logan Rettino never imagined she'd fall so far. Dropped by her ex on national TV, she's gone from prima ballerina to ring card girl, reduced to revving up the crowds before MMA bouts. However distasteful she finds her new job, it pays well…and she needs the money if she's ever going to rebuild her life. Promised a huge bonus if she can convince a brooding, gifted welterweight to keep fighting, she'll do whatever it takes to earn his trust.

Keane O'Shea is unbeatable in the octagon. A former marine, he fights with a ruthlessness no gym jockey can match. He knows his brutal strength is too much for the delicate ex-ballerina, regardless of how fascinating he finds Logan's tight dancer's body. But one private performance and he's drawn to her in a way he can't—or won't—resist.

As Logan discovers the heartbreaking truth that lies beneath this handsome warrior's rage, she'll need to forfeit everything she thought mattered for the one thing that matters the most: saving Keane from himself.