Iran’s president-elect, Masoud Pezeshkian, walked through a leafy cemetery, glanced at tombstones and sat by the one bearing his wife’s name. Moments later he was riding in a car, weeping.

The scenes were captured in a campaign video addressed to his wife, Fatemeh. “I miss you more than ever,” the narrator says, speaking on behalf of Mr. Pezeshkian, “I wish you were here with me in these days when I have made this difficult pledge.”

Public declaration of love is an anomaly among Iranian politicians. Crying on camera for a romantic partner is even rarer.

But Mr. Pezeshkian, a 69-year-old cardiologist who won the election in an upset as a reformist, looks and sounds unconventional.

He has portrayed himself as a modern leader for a new era in Iran, a religious man who considered his wife an equal partner when she was alive — and like him, practicing medicine — and who was a devoted widower after her death in a car accident. He raised three children and never remarried.

“It’s very interesting how he has used his family story as a sign of his commitment and reliability,” said Ali Vaez, the Iran director of the International Crisis Group. “He promised that in the same way that he stood by his family in the absence of their mother, he would stand by the Iranian people.”