Too Lethal to Love (Project Viper #2) by Kristie Wolf:
 
HE THINKS HE’S TOO LETHAL TO LOVE.

Lieutenant Kane Darren lives by one rule: serve first, love later.

His allegiance is to Project VIPER, the top-secret military program that turned him into a super soldier. Now his bionic body and his mind are deadly weapons, but that’s not why he can’t chance falling in love.

Enter the snarky scientist who shines brighter than a Christmas tree. He should stand down and let one of his teammates protect her since she doesn’t like him anyway. Well, too bad. Her vacation plans now include him.

He’ll need a holiday miracle though. Not to stop the threat, but to protect her from himself.

SHE THINKS FALLING FOR HER IS FATAL.

Kane thinks he’s invincible. Against a drug cartel, he likely is. But the rugged cowboy with the superpowers and the sexy twang doesn’t stand a chance against Dr. Beth Parker and her deadly curse.

Beth should be worried about the threat to her life, not the blazing chemistry she can’t deny, but the proof is in the graveyard. Loving her is a ticket to the morgue.

She can’t let Kane be her next victim, even if protecting him puts her life at risk