Serious relationships???

I came back to CS, because I enjoy reading the blogs, but not being a member, I couldn't post any comments or create any blogs.
Since coming back, I've exchanged mail with some men who wrote in their profiles that they're "looking for a serious relationship", yet when they ask if I would make love or have sx with them, if and when we meet, and I reply "no" all mail contact ends. Does having a "serious relationship" these days mean that I have to have sx with a man within minutes/hours after meeting him in person? I always thought getting to know a person and finding out if there's any chemistry before taking it to the next level is how to start a serious relationship (although I've heard that some serious relationships start with sx at the first meeting). I'm not old fashioned but know from experience that some relationships that start with sx, end up being just that.....sxual attraction and nothing more.