Why do I feel so insecure when I’m not in a relationship and how can I overcome this?

You must first heal your past trauma before you enter into a relationship. If you are already in one then know that it is up to you to fix not for your partner to fix for you.

Think of the things that makes you happy you aren't in one. Being single doesn't hurt if you know how to be content and happy with what you already have

Being by yourself is much easier...how can you be comfortable in a relationship when you are not comfortable by yourself

stay single until it feels normal. it will take a while, but not as long as you might imagine.

Make a great life for yourself.