Kim M. Catullo does not like giving interviews or getting behind a microphone. At political events, she tends to hover in the background, so much so that she is sometimes mistaken for a member of her wife’s security detail. But with the primary just weeks away, Ms. Catullo, the wife of Christine C. Quinn, is edging out of her comfort zone to take on a more visible role in Ms. Quinn’s campaign for mayor of New York City.