Knox by Anna del Mar

Knox Lancaster is a cocky, insolent, roguish ex-SEAL who walks the earth as a scrumptious Stetson-wearing cowboy and has never been denied what he wants.
Until Karma catches up with him.
Karmen Roa—aka Karma— is a scrappy, one-shot, one-kill sniper with an attitude problem and a mouth that can shoot just as fast as she can pull the trigger. She’s also gorgeous and dangerously hot in bed. Knox knows. He’s been burned by her heat once before.
Unfortunately, she also has that stupid one-guy, one-night, no-repeat rule that she refuses to break. Knox likes his whiskey neat and his women fierce, but this woman?
She just might prove to be his downfall.