-He likes Moana more.
-His family likes Sarah more.
-He is a wuss.
-He also doesn't REALLY like either of them enough to see them much past what is contractually obligated, and he has to live with his family's reaction no matter what (although of course we will hear lots of false "follow your heart" comments from them before this is over, no matter how much or little they mean it).
So he will pick Sarah. Give her a promise ring, not an engagement ring. And hightail it out of town to his new practice located nowhere near where his family, or either girl, lives, letting the supposed relationship just sort of whither away until the public forgets about it.