Reject someone is not being nasty. Many women react to strangers in the street the same way that men would react to a stranger in the street: cold and keeping distances. It seems nasty because you have been used to women going out of their way to be nice so by contrast it seems "nasty". But I bet that they don't react the same at a party when they meet someone, than at the street. It is the place, the situation and the mood.
I mean, in Europe people go to bars or pub to flirt. But if someone does it at the street or the underground or other place with a perfect stranger, then there is something off. Sure, you can meet at the gym and once there is some relationship try your luck. Or maybe you meet at some other place. But a random stranger of the street? You might be received as someone trying to sell you crap, because is weird at the best case scenario.
And being rejected is not hate, is indiference. It is a the same level than a woman you are not interested in and you choose to ignore (totaly OK). If she like you, it might sting, but it is not hate, just indiference.
As for the dismissal methods, in my experience, the nicer ones doesn't work. The man keep insisting and ignore the rejection. Since the polite methods are ignored (because men seem to think that they must insist), women "scalate". That means, using more clear rejections. Those clear rejections are harsher. It is something you learn over time, men would push and pressure you if you are nice. Since saying "I have a boyfriend" no longer works, the next best solution if you are not interested and want to keep it short is a more blunt response.
I'm afraid it is cause and effect. And I get if men decide that they no longer want to approach. I don't blame them. But my advice is that they better use the other methods that work best: introductions by common friends, activities you like where you can meet people and go to the places people go to flirt like pubs. Also, take the first rejection, which is usually more polite than the ones that comes next.
Dating apps or single events are also a good idea, since by being there, people are saying that they might be open to approach. It is about place and situation. The same single woman might be happy to be approached at a pub, but unhappy to be approached at work. I mean, I'm sure that something similar happens to men. The right place and the right moment go a long way. Thinking about those things shows consideration which is what for many women identigy "the good ones".
