Proviso, comment is based on old memories.

There was some research done on how women flirt. Women particularly put out IoIs (Indicators of Interest). These include things like hair flick, lip touching etc. When a woman is attracted to a man, the rate of IoIs goes up, sometimes 200-300% baseline.

Unfortunately, the catch is the baseline. Women vary widely on this. Some normally use 2-3/hour, others all the way up to 120/hour. This is where men can often get in trouble. A woman sending them 60/hour might be a 20 flirting outrageously, or a 120 who is actively disinterested. Trying to advance things will get vastly different results with these 2 women.

Because of this, a lot of men get risk adverse. Even if they pick up on the hints, they are not sure if they are reading them right. Conversely, a few men go the other way. These men tend to have a disproportionate, problematic effect on women. This is why most men don't think that sleazy, overly handsey men aren't much of a problem, but women vastly disagree.

Basically, men are stuck in a "damned if they do, damned if they don't" situation. Even worse, the men who figure things out tend to find a good partner and pair up, taking them out of the pool.

To add to the confusion, what women say they want, and what actually works can be quite different. The same applies to men. However, since men are generally expected to make the first move, they tend to screw it up a lot more (and get burnt).