He gave her up to save her...
Murphy knows the kind of life he lives with the Banachi isn't for everyone. Danger is always one step away and that's why he pushed away the woman he loved five years ago. He had claimed Tatum for a brief moment, but knew he couldn't keep her if he wanted her to be safe.
Imagine Murphy's surprise when that danger comes straight for him, and throws Tatum at his feet.
Murphy needs to decide if there is a place in his life for Tatum or break her heart all over again. Either way, they're both in danger.