Without going through 14 pages of replies I just though I put my 2cents in based on the OT.

I dont think sex is a must during dating and bf/gf period, but would help in one - like some here who have already said.. it is a plus in a true relationship where both party genuinely love each other. Sometimes it could also be due to religion where being abstinent is called for and both partners should also respect that if the other observes it.

But then there are also relationships whereby the girl could potentially be a demanding type (im a guy btw) who would be spending (his) money like nobody's business or takes up a huge bunch of the guy's time... and as shallow as it may seem sometimes sex maybe a good indicator of weather the girl is just taking the guy for a ride. (assuming she is not a slut).

But after marriage I did say sex is a must. Otherwise I cannot see how else a couple could bear children.

I guess couple dynamics is a lot more complicated then we can have it written here. At times it is actually best to set some ground rules even before getting into one relationship or taking it to the next level... test the water before hand or even ask if it is not plain enough to the other party.