Well, I used to be similiar. I used to rely on other people for my emotional stability or just to make me feel good and safe. I was really clingy. Then I started thinking that I was tired of the roller coaster because usually, people are unreliable. Besides, people have their own lives to live and they can't be there for me every five seconds. (That's what I started thinking.)
There's a concept called, "healthy detachment" that I began to practice. I would still love the people that I let into my inner world, I'd still be concerned for them, yet I would be able to let them go. It took a lot of focus and I had to keep reminding myself that just because I let this person into my inner world doesn't mean that I have some claim on them and make them a prisoner of my inner world.