Hi and welcome. I am a Licensed Master Social Worker with more than 20 years experience working with individuals and families on a variety of issues. In order to overcome the fears
it is important to understand why the fears exist. If you haven't had the benefit of counseling, then i would suggest that so that you can have your safe space to process what it is all about.
The fears often come from worry about losing oneself and independence in a relationship or fear of being left by the other person if you fully let go and invest.
these can be scary things and every relationship can bring this stuff up, but with the right person and understanding of the reasons why these fears exist, it is possible to overcome it
if the fear has only existed with this one particular person, then it may be that you don't feel as connected as possible.
if this fear has shown itself in all relationships you have had then getting some counseling to understand it all will be the way to go to learn about yourself and overcome it all.
I will wait to hear from you.