LAST July, Kelly White and her boyfriend became engaged. They had a cozy picnic of wine and cheese on a hill before he presented her with a watermelon-flavor Ring Pop and asked her to marry him. “I’d rather not say if he got down on one knee or not,” she said. “It’s embarrassing.”

But they won’t end up at the altar anytime soon: they said they would not marry until gay and lesbian couples are also allowed to.

“I usually explain that I wouldn’t go to a lunch counter that wouldn’t allow people of color to eat there, so why would I support an institution that won’t allow everyone to take part,” said Ms. White, 24, a law student at the University of California, Davis. “Sometimes people don’t buy that analogy.”

Whether it makes sense or not, some heterosexual couples, mostly in their in 20s and 30s, are protesting the inability of gay and lesbian couples to marry by putting off their own marriage. Unless wedded bliss is available to everyone, in every state, they say, they want no part of it.