I hope you are not a surgeon, But a general doctor. Anyway :
1. Have you introduced that fellow to your parents. (Even as friend)
2. Have that shown respect for your parents.
3. Problem is with other caste or fear of rejecting by family members? What is real problem. If your parents are nice at heart, then why fear? Be strong enough to live your life and convince softly.
In our childhood, many times happen (specially cricket team, Bully team keep on throwing coin for toss until they win.) Why are you playing the same rule in life. Take a decision. Accept as wish of Sai and move ahead. If a doctor keeps on pending issues of his own, How it will react on critical diseases of the patients who come to him believing another form of God to cure them.
You are wise one, so need not to say more. Baba’s blessings are already with you!
om sri sai ram!