I didn't get a sense of fear of intimacy from reading your post but more of a habit sort of thing. You allowed yourself to get use to masturbation rather than interaction with another person; it's kind of like what happens if we fantasize too much during sex, we're lest "present" and that can get in the way of a relationship with a particular person.

I would share your "preference" with your love and see if she isn't willing to help you change the behavior, if you and she both want that? I think if you do a lot of touching/cuddling/tantalizing with promises of more afterwards, might help you think differently/that the act is "worth it"?