When He Fights by Cynthia Eden

He saved her from a nightmare.
Once upon a time, Kane Harte rescued Anastasia Patrick from hell. He took her away from a killer, protected her, and maybe even came perilously close to loving her. But then she was given a new life. A new name. A new home. And there was no room for Kane or the darkness he carried in her new world. So he walked away. Didn’t look back. Fine, maybe he looked back a little. Or a lot. Maybe he dreamed of her every time his eyes closed. Sue him.

She falls for bad guys. It’s a quirk. A flaw? Whatever.
When her ex turned out to be a killer, Anastasia “Ana” Patrick knew she was in trouble. But enter the FBI—or rather, enter the super scary, slightly shady, and undeniably hot Kane Harte. He protected her, he gave her a new life—new name, new home, new Ana. And he also broke her heart. That would be the previously mentioned issue she had with bad guys. She fell for the dangerously secretive Kane, and he walked away