1 Book Found

Based on your description:

"* The heroine is a travel nurse from the U.S. * She takes an assignment in Puerto Rico, specifically in or near San Juan/Old San Juan * She rents an apartment while she’s there * The hero is her brother’s childhood best friend * They grew up knowing each other because he was always at her house * The hero has secretly been in love with her and has been keeping tabs on her for years * He’s wealthy * The heroine ends up in danger and the hero goes to Puerto Rico to find/protect her * Puerto Rico is only the first quarter or so of the book, then they return to the mainland U.S. * The hero has ties to the Italian mafia through his estranged father * He was not raised in the mafia world and grew up in a small town away from those connections * The heroine’s brothers are alive and are active characters in the story * There is no significant age gap * It felt more like romantic suspense/protective hero than a super dark mafia romance"