In a day and age where finding people to date on apps or on social media such as instagram is the norm, it has become incredibly easy and normal for people to be flaky, unreliable, to text or say the wrong thing during a date which completely turns the other person off and to feel shit as a result of someone you thought would value your time disappearing forever while ignoring you and making you wonder where you failed to spark attraction and interest.
For people with low self-esteem, it is incredibly easy to always blame this on themselves tho and to take this stuff personally. They might start overanalyzing the situation and give it more time and energy than it deserves rather than just moving on.
However, the truth is that sometimes, people are simply unreliable, have flawed thinking, are insecure or guard themselves from getting hurt to the point where it is not possible for them to ever have a relationship since they are never vulnerable and always assume the worst from people/always assume the role of the victim.
Those people are the ones who seem to be extremely hard to satisfy on the surface and who believe that nobody is good enough for them because all they pay attention to is what other people are lacking rather than focusing on what positive qualities people have. The scientific term for this is the Baader-Meinhof phenomenon. This is a cognitive bias. A cognitive bias is a systematic error in thinking that affects the decisions and judgments that people make. Some of these biases are related to memory. The way you remember an event may be biased for a number of reasons and that in turn can lead to biased thinking and decision-making (source: https://www.verywellmind.com/what-is-a-cognitive-bias-2794963 & https://science.howstuffworks.com/life/inside-the-mind/human-brain/baader-meinhof-phenomenon.htm ).
So in short, judgements people make about other people are clouded and inaccurate as long as they are not based on facts and only on their experience.
The reason a girl with biased thinking rejects you can be because she associates your charming and seductive nature with the belief that all charming and seductive men are cheaters, liars and abusive because all her exes who were just as charming and seductive were the same (which makes her feel uncomfortable and thus want to avoid you).
The reason a man with biased thinking rejects you can be because he associates your caring, loose and easy-going nature with women who want to take advantage of him because all women who were caring, loose and easy-going in the beginning ended up taking advantage of him and thus he avoids and rejects you, even if you are not the same in reality.
So the next time you take rejection personally, keep in mind that most people have flawed thinking and reject you because of their own issues, not because of you.