Love Changes Everything by Peri Elizabeth Scott

Simon has developed feelings for the girl who bedeviled him growing up, his best friend’s sister—not that Alys is a girl any longer. She’s a grown-up, beautiful, wonderful woman who makes him crazy. He obtains her brother’s permission to date her, and asks her out. And is rejected.

Alys is innocent and plans to stay that way until she meets a man who holds the same moral code, regardless of her lengthy crush on Simon. Privy to his escapades and conquests, her jealousy has turned to distaste and she sets herself on a different path.
She wants a man who has refrained from meaningless affairs, who has waited for the special woman.

Simon does the research but Google assures him he can’t become re-virginized and thus Alys is beyond his reach—until one day when he takes her for lunch in his beloved truck. That day, love changes.