So I recently decided to pick it up and look through it.
I can't take too much of that bs at one time.
On an intro level, it's obvious. Duh. If someone isn't making an effort to pursue you, of course they're just not that into you. Been there, done that, and it only took a handful of rejections after I did the asking to figure that out myself, without some Sex and the City book to tell me that.
I do not really think it is always as simple as that once a deeper sort of relationship or friendship has developed.
Then again, I just started it, so I could be wrong. OMGZNO!