How can I overcome fear in my relationships?

Talk therapy. It would be important to first understand the nature of your fear in relationships, so that this can be effectively addressed. Lots can go into this. A trained psychotherapist, or psychiatrist who does psychotherapy, can help you explore and deal with it. Most people desire healthy relationships, so you are surely not alone in wanting to improve yours. Good luck to you.
Relationships. Obtain help understanding the origin of your fear and then work on developing actions that can dissipate your fear, a mental health professional can help you attain this goal. Best.