There could be many reasons for anyone to stop when just about to have sex or during it. For example, for some people the shape, texture of the genitals are very important and very strongly influences what they feel at that moment. Some people do not even think to kiss or suck (just simple sucking, not giving head) their partner's vagina/penis, while some cannot imagine a penis getting into them if they do not feel the desire to put it in their mouth when they see it. I am somewhat in the second group. I need to love a man's every inch. Esp. his penis in a 'seperate' way from his body. I need to warm up to it. If I don't want to kiss, lick suck..etc that man's every inch, I don't want him in me. And most of the time you get that when naked. Sure, this is not absloute. Sometimes you like somebody as a person in time, they grow on you and so how you see their physical appearance changes. But some times it goes the other way. You find someone attractive all along, but that disappears when they get naked. Sometimes, you feel horny and answer someone's advances, someone you know that is wrong and after getting into it, you come to your senses. Sometimes, someone you never guess, can speak to your skin...etc. We could work countless scenarios here.
People can call stop and get out of it any time. Consent is not just given once and done. It can be taken at any second. This is as simple as this.
Sex is awkward, messy, embarrassing at times. It's not something that is done to be perfect, aesthetic or watched from outside. Sure, we love to wach people having sex. But that's scripted. It's an act done by professionals. Real sex is never like that as we all know. It's between the people doing it. Anything can turn somebody off in any second or rise their apetite. You can accidentally fart, get a cramp, hit each other somewhere wrong while jumping on each other, have another accident...etc.
Apart from a few women who enjoys playing their seuxal power over men, this 'leading men on' thing mostly comes from the old patriarchal oppressive conditioning. The bullshit that men desire sex more than women and that they need it more than women and that they are mindless puppets once you turn them on, that you can make them jump hoops by showing a nipple, once blood walks into their penises so they should be emptied before they get functional. It has been used for control,to excuse rape, to subjugate female sexuality. Humans have impulse control.
What's the merit of 'leading on'? I've known a lot of men, western or eastern, even online, who thought looking into their eyes, smiling and laughing at their jokes while talking excitedly, paying good attention to them in a heated conversation, discussion meant for them that I was interested in and touching their shoulder, arms, face for example was a sign of 'leading on'. It's bullshit.
Especially, personally that's my experience with western men, because they come from less sexually oppressed culture, they are more likely to openly take anything as a sexual hint. The culture I live in, as it's a greater taboo, mostly people don't dare to show it that much.
Sure, may be for some people those things are not leading on, but what is what to whom? Because if you are naked with someone when they didn't want to go further, they simply stopped desiring you, because something happened and this could happen to anyone. Men are not entitled to get their way, because of the mechanics of their genitals.
Men need to get out of the frame that men are mindless pussy idiots. Because not just some women, but mostly men treat men and themselves this way. And also the bullshit that being rejected by a woman means something is wrong with their manhood. The collective idea -hopefully changing with the young generations- that they are ready -should be ready- to jump on very pussy available around is a very stupid base for social norms. I don't find one man attractive, however others do. Same goes for me. A man can find me attractive while others don't feel anything- may be even turned off by me...etc.
Most men have a way of making this a goading issue, a competition, a score among themselves and so it gets blown of out of proportion. (Like the penis size issue. Men are more interested in penis size than any woman.) You can watch some men who never had an experience on this 'cock teasing', speaking about 'cock teasers' as a rule.
Your penis is not something women should obey when erected that has to go to the finish. Exactly like the way a woman doesn't have a right to expect the perfect erection from you the moment she takes her clothes off. You can lose erection when a woman gets naked too.
Does anyone blame men for leading the woman on in that case, when they do not get an erection? No. Have you ever heard somethin called 'pussy teaser'?
However, with most men, being rejected while they are about to have sex is something about their manhood and male ego in general, more than facing a simple rejection by someone. It's just that, rejection. She is not turned on by you. Another one will be.