Living with your boyfriend is fun. It also can be practical, meaningful and a sign of deep commitment. But as if to confirm the fears of nervous parents around the country, a new study in the Journal of Family Issues says that couples who live together are much less likely to wed than they used to be. That's right, Mom: according to the study, entitled "First Comes Cohabitation and Then Comes Marriage?" two thirds of cohabiting couples in the 1970s married within three years. Now only half as many women walk down the aisle with their live-in mate that quickly. Among all cohabiting women, one out of four says she doesn't ever expect to marry the man she lives with. (The expectation of marriage turns out to be an excellent predictor of actually marrying.) Pamela Smock, a University of Michigan sociologist and coauthor of the study, says that what motivates women of all ethnic groups to tie the knot is finding a well-educated man with a stable income. "If we want to promote marriage, economics are essential," says Smock. But many couples say that, good job or not, they have no desire to wed. "I can buy my own appliances," says Teri Hu, who has lived with the same man for 14 years. "Watching our peers get married and then divorced has really enforced that this is a much better choice." And, best of all, it means your friends never have to sit through a honeymoon video.