Out of Nowhere by Rebecca James

Sometimes, you have to leave your comfort zone to get what you want.

When Dex and Seo-jun are paired on a case, Dex is both nervous and excited to work closely with his secret crush of the past two years. To his delight, Seo-jun begins to open up to him, and, in return, Dex tries not to stare in open-mouthed wonder at his beauty. If only he wasn’t juggling his bodyguard duties with his usual tech work, his sister’s problems, and his mother’s interference, maybe he could enjoy himself.
Burned by love at a young age, Seo-jun hasn’t given romance much thought in the past decade. Until Dex. The cluelessly sexy tech specialist at Falcon Security has been teasing his way under Seo-jun’s skin for months. As partners on a case, the two men have to share a bed in their client’s home, and no one’s more surprised than Seo-jun that he enjoys those moments in close quarters. Dex is easy to talk to and fun to be around, and Seo-jun feels comfortable with him–something he doesn’t normally feel with people. It isn’t long before Seo-jun comes to the realization that, if he wants to be with Dex, he needs to change some things about himself.
Seo-jun soon learns that issues left undealt with will eventually resurface, and as Dex tries to help him face his past, Seo-jun attempts to be supportive when Dex finally gets the courage to come out to his dysfunctional family.