Sounds to me like Jason's girlfriend has the right idea.
Taking gender out of the equation, consider the following:
When you are getting to know someone that you have a good rapport with at first (buddies, girlfriends, etc.), have you noticed that you tend to look for what's positive about them, about things that are common between you, reasons to like that person more? But at a certain point, once you get to know a person well enough, you see beyond the facade you've created. If enough negative things come out, you choose to see more and more that you don't have that much in common, that this person isn't as cool or nice as you once thought they were. This syndrome can lead from "I love her!" "She's my soulmate!" or "What a great guy!" all the way to "What was I ever thinking by liking this person?" "Why did I ever date her?!?" "How could I marry that awful witch?!"
My point is that what you see, depends very much on what you are looking for, and for me, this helps explain why some relationships sour after weeks, months, and for some years. People absolutely do change, we all know that, and that's why it's never a bad thing to put off marriage when in doubt (Hello O-Ring).
In my brief 5 years of marriage, I've decided for myself that one of the best questions a person can ask themself before they get hitched is, "How well do we solve problems together?" or to put it a different way: "How well do we settle our differences?" Or how about this one: "How well do we treat eachother while we're solving our problems?"
Invariably, if the answer to any of those questions is "not very well", then I don't see a good foundation for a lifelong relationship, as we all intend marriage to be (unless you're a contestant on Joe Millionaire).
In my mind, no matter what, if you're with a person for long enough, you're going to get past all of the positive things you see (and are looking for) at the beginning of the relationship. You'll see all of his/her negative attributes, all of the differences between you. Your expectations at that point will be much more realistic, and I think you'll have a higher chance for success.
I'm not sure what's more important when it all comes down to it in relationship success: expectations or how you treat one another. But I do believe that there's just not enough civility and respect in the world, let alone actual love. And as a wise man once told me, love is an act, not an emotion.
A pedestal is a precarious perch. Careful who you put up there.
Rick