Hmmm… excuse me while I attempt to suspend disbelief. Heroine is military. She's trailing a guy who disappeared under her command. The guy is a Navy SeAL. What exactly is she that she'd have command of special forces? And we aren't talking desk job command either - she apparently has known and worked with the guy for some time.
So Ms ball buster without a single feminine streak sees the H and starts having fantasies about him. She can't make herself stop having fantasies about him. She gives in to impulse and buys tramp clothes to catch his eye. Em… Ok.
He of course has issues - once early on in his days as a vampire, he thought he was in love with some chick, and told her. She panicked and told the nearby town. Poor guy nearly got himself killed. (I'm thinking if the chick bolts, it's time for you to find a new hidey-hole, dummy) So he freaks out when she sees him all fangy (due perhaps to her military training, she's too disciplined mentally for him to influence her). That was actually a bit entertaining there. Not so entertaining was her going after the guy during daylight and finding out that A) he was turned into a vampire - that's why he went AWOL during a mission and B) a prior uptight heroine's slutty sister apparently had a personality transplant and married him. Ehmmm… yeah. I think an explanation was in order about that last one in particular.