As she had been secretly in love with him for a long time. Staff Nurse Deborah Culpeper should have been thrilled when the distinguished Dutch surgeon Gerard van Doorninck asked her to marry him. But he had made it clear from the start that his reasons for wanting a wife were practical not romantic - in his position he needed a hostess, and it had to be someone competent and sensible unlikely to try and make complications out of the situation: someone just like Deborah in fact.
So Deborah married him realizing that she must accept Gerald on his own terms and see how it all worked out. It might indeed have worked out very happily -- had Gerard's friend, Claude van Trapp, not done his best to try and spoil things!