Couples who are already engaged who move in together to save on living expenses before the wedding, for example, are just as likely to stay together as couples who wait until their wedding day to share a home. In fact, some studies have shown that the early days of marriage are actually happier and easier for those who adjusted to living with each other in the months leading up to marriage. That's exactly what I've done. Once you decide to be married, the extra $1000 or so spent to remain in separate living accommodations starts to seem silly. A year of saving that money will help accumulate a nice downpayment...
Or pay for your wedding.