Are you afraid to be alone? Were there people in your life that left you? I think everyone was left at some point. We thought we were important and eventually we were left on our own. That can be done in number of ways. Do you need others to know your true value? Well, most people need. Unfortunately, it can be easily exploited by someone. The best way to avoid emotional manipulation from someone is to learn to be alone and happy about it. That way, you will not be at anyone's mercy. I don't think it is easy, in fact I think it is very difficult. It is somewhat natural for introverts but for extroverts it must be really really hard. They need other people to feel comfortable all the time. Having lived for a long time I have noticed that people have tendencies to exploit our weaknesses once they find them out. In that sense extroverts have a really hard job because they are constantly exposing themselves and therefore are vulnerable to be hurt. They need others.
To your great surprise dear reader, I have found that there are very few people in my life that at some point didn't want to trick me, fool me or use me. People are really cruel, so to be at their mercy can be a real hell.
There are precious friends and precious friends are hard to find. That is why I had to learn to be happy about my solitude so that no one will be able to exploit me and use that against me. I recommend that for you dear reader as well.