No, it should come after the relationship begins.

sex must come after the relationship begins. being totally honest, I would get frustrated if my girl and I didn't have any sexual intercourse. remember that sex is the other important 50 percent in a relationship between a couple.

well, in a business relationship it is a little tricky. I often suggest sex with my boss and coworkers, but nobody seems interested. If they are interested. . . YEAH!

Maybe, people think that it is but it must be only when man and woman get married.

It seems that we who have answered that sex is for married couples gets the negative rating. I infer that the norm nowadays allows the contrary and considers it as an important ingredient in a relationship. @Dano It is true that you can't love a person you don't really know. In our culture, we have the courtship first and the dating process before a relationship stage. (This is the 'relationship' that I refer to) In courtship, you'll see if you like the person If you entertain the person, then you go dating. That's when you'll weigh if you love the person and would like to go serious (enter relationship). If you don't love the person, then don't commit to a relationship. Also, being in a conservative country, pre-marital sex is still a big taboo to us. Maybe that's the reason why the asker asks this question- To know what's the practice among other cultures.