A Lass for the Billionaire by Donna K. Weaver

Nurse Eve Stewart is excited to take on another bucket-list fulfillment trip, this time to Edinburgh. That is, until she discovers who’ll be spearheading it: her high school best friend who kissed her and hasn’t spoken to her in twelve years. She doesn’t expect her old feelings for Darius to come alive. When they do, Eve must decide if she can learn to trust again.
Billionaire Darius Dimitriou doesn’t want to take over a fledgling bucket-list charity. When he finds out the project’s nurse is the girl he secretly loved in high school, he changes his mind. As they spend time together and his love for her rekindles, he begins to hope they might have a second chance. But first he’ll have to share his past, and it could kill any hope of being with her.