Don't look at the donated husband's teeth

Sienna has no intention of getting married and certainly no plans to have children. However, when she is caught in bed with her lover by his wife, and instead of the expected scene, she literally "gives" her husband to her, Sienna and Bork live for many years in a quite happy marriage. But then she finds out she's pregnant, and she's desperate. Because of an old trauma, she decided to remain childless, and suddenly fate had her on the run.