Anytime I meet someone amazing and we have great chemistry I mess it up because I worry that he will leave me anyways.
Do you let them know how it makes you feel whenever this sort of thing happens?
I just tell him that I love him which ruins it.
Everyone lacks confidence from time to time, but you shouldn't constantly worry about things that you have no reason to believe will happen. If you meet someone who you have good chemistry with, he wouldn't want to leave you. You should have more confidence in yourself.
You have good points and I'll try to talk to more people in the future, even if I don't trust them.
That's good, you shouldn't worry so much about things that haven't happened yet or may never happen. It is a lot healthier to believe in yourself and hope for the best.