The way I see it, why should you stop treating them so well when you get married? They choose to spend the rest of their lives with you, the least you can do is occasionally make them feel like they're worth your time.
If a girl falls in love with you and chooses to marry you, they're basing that decision on how you act when you're still dating.... if you immediately change after you get married and stop doing all the "nice" things, it'll leave the marriage dry and almost disappointing.
I'm being very harsh there (sorry), and I know there's a lot more to it, however that's my take on it anyway.
