For romantic relationships, what I used to be afraid of, was mostly to be with someone I don't love fully, or as much as the other person loves me. The very few times I dated someone I wasn't fully into it, somehow ended up in a relationship because they treated me beautifully, rather than because I loved them more than I would a friend. That didn't work, and hurt the other person as well as created a lot of turmoil for me. To the point where I accepted the fact I wasn't made for it.
I ended up with someone I love more than anything or anyone, and it's the same for him, so never say never.