It held promise but... It's somewhat amusing how authors tangle things into a gordian knot to get H/h from point A to point B.
Ok. H was in hiding. Got that. He'd seen something, testified, put someone away, and been nearly killed for his efforts - while under witless protection.
The h gets to spend time with him after he manages to make himself sick, and a) notes a gun in a kitchen drawer, b) he's terribly jumpy, c) the way she broke in freaked him out, etc. At no point does it ever cross her mind that maybe he was on the run from someone or something.
Much later, after he's tried to scare her off, and given up on that idea, she sees his scar and he eventually tells her about it. Still not putting 2 and 2 together.
It's only *after* she's involved in a hit-and-run, and he takes a runner, *after* she starts looking for answers and finds out he's supposedly dead (which, btw, was near the end of the book) that she gets it, and that only after visiting FBI headquarters (I raised an eyebrow about that)
And she finally corners him - he's been shadowing her - and they have closure because the person after them conveniently is the bad guy's son, and not v. bright since he makes an attempt in a hotel room. Of course, she's not v. bright since she opens the hotel room for flowers...while they're pondering there still being someone after him.