Undercurrents by Traci Hunter Abramson

Shaye Kendall, an Olympic-bound swimmer, has been in the witness protection program ever since she witnessed her boyfriend's murder.  She now has a new name, a new life, and strict orders not to reveal her secret. But fitting into a community is hard when you can't tell people anything about
yourself.  When she learns that one of her new friends, Matt Whitmore, is LDS, she can't even tell him that she's a Mormon too.  She doesn't dare get involved.  The fact that Matt's father is a high-profile senator could give
her the kind of exposure she doesn't need.  How can you fall in love when you can never reveal who you really are?

But when someone almost takes her life, Shaye recognizes that whoever is after her knows exactly who and where she is.  Can she trust Matt to help her?  Can she trust his family?