Here's where David enters the story. Years ago when he was in the Navy, David had checked a box on a form agreeing to be a potential bone marrow donor. Although doctors had told Diana her donor would likely be of Puerto Rican heritage, David (of Scandinavian decent) was a perfect match! David's bone marrow saved Diana's life.
Diana wanted to thank her anonymous angel in person, but for months he declined. Eventually, he relented and they talked on the phone. When they finally met, their instant friendship turned into mutual attraction. They developed and long distance relationship and fell in love—now they're engaged!