Why do I feel weird and distance myself when I become close to someone?

I have been like this my whole life. Basically, when I get very close to someone I tend to opt out and emotionally distance myself. This is one of the reasons to why I have never had a best friend or someone I can entirely confide in. I sure have good friends, and I'm liked by my friends but I get uncomfortable if we become too tight. I feel so overwhelmed and not comfortable. Most of my friendships are shallow, except the ones where I have known the other person for over 5 years. Shallow in like, they don't know a lot about me outside of the partying/getting a coffee together/seeing each other in school.

As an example. I recently started college and have become tight with some girls in the same dorm as me. We party together and we've even had sleep overs etc. We get along great and me and this girl have bonded quite a bit, as in we can talk about everything even though we've known each other for 3 months. But now, I feel way too uncomfortable and have decided to distance myself a little. I don't talk as much with them as I did before and I give them made up reasons why I can't attend a party they are hosting next week.

I notice that I've behaved like this since I was a little kid, and maybe it could be a reason why I don't have "best friends" or people I hang out with regularly. I just don't understand how every other person in my age can form stable and intimate relationships with others while it feels so uncomfortable for me to do so. And since I'm a girl, I feel like it's expected of me to form intimate platonic relationships with other women? I feel like a freak for not being able to do so.
Some help and advice would be appreciated. I think I might have a serious issue with attachment to other people.

It's sounds like you're a loner.

Did you come from a home where you were emotionally neglected? If so, that would explain it as emotional neglect turns people into loners as they were never provided with the emotional closeness to learn to bond with others.

What is your sense of "get very close", if I may ask. I mean, an acquaintanceship is less formal than a friendship, which is in turn less formal than a not-only-platonic relationship.
I understand.
If I may give you my situation: I have a net of 3-5 "core"-friends, friends who I know for several years (> 10 yrs) or I grew up with and I can confide totally into. Then I have a few friends I am not that close, but try to maintain the friendship. And then I have acquaintanceships which I see on occations.

However: For my life so far I couldn't hold a single relationship above the state of friendship. I almost certainly blow it at the earliest possibility, and thus didn't had contact to those "tried relationships" except for one, which I tried in the age of 10-14.
Sounds you rushed the relationship in your own eyes. Perhaps you can re-ignite the flame of friendship by restarting the process in a more slow manner.
I, for my part, had besides a very few relationships that lasted, also no real "best friend" ... considering, that almost all my friends are older, partly significantly, I would say I can imagine what you mean.

Full disclaimer: I am male. So I can't say what is "usual" between women. However I have been told several times, that I am from my character quite similar to women than typical male.

If I may give you advice: Next time try it a bit slower ... it takes time to know the right speed that feels right to you in order to progress a relationship.

Kindest,
rewin

You are probably afraid of trusting people since you, just like many other people, have been done wrong before.

Yes, I sometimes got the silent treatment from my parents and other types of emotional abuse.

I don't feel like I'm a loner though. More an introvert. I like being alone and doing things on my own but want some company time from time. It's just that I can't keep up with intimate and deep relationships. Shallow relationships are great for me.

But I realize that I will end up alone if I keep acting like this.

Get very close - someone I trust and can talk about anything with. Someone I enjoy being around. Someone I have chemistry with.

Yeah. But as I said, I don't think everyone that have been done wrong acts like I do. It seems like my problem is a little bit more serious.

Maybe part of the problem is because you didn't have a close relationship with your parents so you don't know how to be close to others. I grew up being emotionally neglected so I can relate to what you're saying, and think it's why I'm a loner. I'm an introvert but am overwhelmed by extremely close relationships.

A lot of people are like this so unless it's something you feel a great need to change, try to make peace with it.

You might want to read a bit about avoidant attachment.

Understanding Anxious/Avoidant Attachment

I myself was told many times as a child that boys don't cry, and was punished for crying, and just generally found it frightening and unhelpful to ask my parents, particularly my mother--who had narcissistic personality disorder and was an alcoholic--for any sort of comfort or emotional support. Thus I too grew up to be anxious, avoidant, and self-soothing. It used to make me very anxious to get close to anybody. I am doing better now, thanks in significant part to therapy, but I still have some anxiety about people getting "too close" and some automatic tendencies to be avoidant.

(((((ArgIdiot)))))

Just wanted to say I think Bill is onto something with the attachment issue, to me this is not just being an introvert - introverts can and do form deep bonds, it just tends to be with a small number of people.

You can get an idea of your attachment style in this test:

Self Tests by Psychology Today

As Bill mentions, attachment style can change, so it's not like it's set in stone for life.