The fear of rejection is an irrational fear of exposing us born of our fear of rejection, not to be accepted socially. We try to avoid painful experiences, so we hide instead of taking risks. We repress our true feelings and abandon others before allowing them the chance to reject us.
What happens is that normally you do not realize how many people around you accept you as you are: you only see those who do not.
In most behaviors, its origin can be explained in two ways: the innate (evolutionary) and the acquired. Probably the second one is much more important and in any case it is the only one on which you have room for maneuver.
You have inherited it …
The evolutionary explanation is that human beings have developed an inner need to be accepted and to fit into the group because in the past being rejected from the bosom of a family or tribe could mean death.
The fear of rejection is also based on your self-concept (how you see yourself) and your self-esteem (how you feel about yourself):
We all like to feel cool people. If they reject us, reality clashes with our self-concept. How can I be cool if people do not like me? That generates dissonance, mental conflict and affects your self-esteem. Mine your pride. You are not as cool as you think. To avoid that conflict you do not expose yourself socially.
It is likely that you are a person who gives a lot of importance to the opinion of others about you. But if the consideration you have of yourself depends essentially on the acceptance of the rest of the people, you have work to do. Because you can never please everyone.
It is normal for rejection to affect you. The unnatural would be the opposite because our body is prepared to respond to it. If someone tells you that it does not affect you, he is lying to you.
There are people who genetically could be more sensitive to rejection. No matter how much emotional support they receive, they may never be able to eliminate it altogether, so do not worry if that is your case. Start accepting it.
The reality is that you can not decide if you are afraid or not, it is irrational, but instead you can decide how you use the energy it provides: whether to stay paralyzed, flee, or overcome that situation. The fear of failure and rejection is what gives people the necessary motivation to prevent them. Use them wisely.