I have experienced repeatedly.
I had one friend - my neighbor, when I was five years old. Then we started going to school. She found another friends and she ignored me at school. I was good when she did not have anyone better.
For a short time I had in the third class a friend - boy. It could take a month. I visited him about four times. He invited me to date, I didn't understand what is date, but I was happy I have friend. One day he came, I greeted him, he did not answer me and he started ignore me. I don't know why. I assumed that people who bullied me told him not to talk to me.
At middle school was one girl, which behaved to me better than others. Once we had a task to say something nice about some classmate. She wanted me to say she likes to help people. And said about me that I often write homeworks at school. It was true, but nobody said anything nice about me and it with homeworks caused me next problems at school.
At high school I had one friend. I helped her with learning. We played together games, like five-quarters. Once I wanted to tell her something important and she was not interested.
She had in our class other friends. I also considered them to be friends, but they never started to talk with me first, they never joined to me when I was sitting alone.
After completing high school she went abroad. After a year she should return, but she did not return. We've been writing e-mails for some time. She wrote me about her problems (she had friends, boyfriend, she lived by the sea. I didn't understand her problems) And I couldn't describe her my problems and after some time I was unable to answer.
She was my friend but I don't know if the only reason was not it was for her useful and advantageous.
At work I had colleagues, I tried talk with them, go with them for lunch, to sit down to them when they were alone. But it was one-sided.
In the best case, I will try to test it somehow. In the worst case, the man somehow disappoints me when I do not expect it.
That I got to know my husband I consider a miracle.
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Sorry for my bad english. English isn't my native language.