Given the choice, people like to keep their options open.
When researchers asked people whether they preferred to take home a poster they had to keep or take home one that could be exchanged later on, most people chose the latter. But it was people who made irrevocable choices early on who ended up happier with their posters.
[Harvard psychology professor Dan] Gilbert said the finding prompted him to go home and propose to the woman he had been living with: "I always thought love causes marriage, but my data said marriage causes love," he said. "When you lock yourself in something you cannot get out of, you will find ways to be happier. . . . I do love my wife more than I loved my girlfriend, and they are the same person."
--Shankar Vedantam, Washington Post, on the value of irrevocable commitment