Well, I see why this movie isn't getting a lot of repeat business. There are a number of attractive things about it, not the least of which is that the Chicago references are pretty accurate. But it's not very satisfying in the end.
You see, if it's supposed to be a romantic comedy, then the couple should figure out how to grow and stay together. They don't. Gretchen observes that it's not a successful chick flick either, because Jennifer Aniston's character doesn't really grow enough to make it worthwhile, nor is it a tragic love story, because Vince Vaughn lacks that soft vulnerable character that a Nic Cage might have that would make a woman go "Aw."
So the movie is out there failing to deliver, no matter what you try to categorize it as. And if the film is failing to deliver, who's going to recommend it to their friends or want to see it again?