To add to what DJDamage said...
If you don't do this your relationship is doomed to either A. Fail quickly or B. Cause you extreme long term unhappiness
This really should be a natural thing that comes from experience.
Meaning...
The ground rules are for YOUR happiness, because you know what makes you happy and what pisses the fvck out of you.
Think about it.
You have relationship A, something about the other person pisses you off to some degree or something happens and for some reason you break up, call the reason CrapX.
In relationship 2 you take CrapX and use it as a ground rule because you know THAT could cause the relationship to end or produce a bad result.
Relationship 2 ends, now you have CrapX and CrapY.
and so on.
At first these should be a the big things (example below), not little picky crap like "Don't cut yoru toenails over the sink." ... the little things can be worked on later.
Now there is a degree to where you have too much crap (rules) that a normal or avg person could never own up to or remember all the time no matter how much they like you...so don't go too nuts.
I've found that the following works wonders and makes you really seem like a prize to the girl.
Tell her (usually right after the first time she says how much she likes you in some way) "Treat me well and I'll stick around" usually I get a very deep emotionally sounding "I'll try." However, I've always said that because I really meant it. It's a result of experiencing CrapX and CrapY and knowing what I will/will not tolerate.
