* Editors cultivate reliable writers. They call on them when they have a project that they believe will fit their field of expertise. Most editors have a list (even if unwritten) of competent authors who also meet deadlines.
* Editors aren't looking for best friends. It may happen that you build a warm relationship with the editor outside of the field of writing. Immediately I think of two editors who have become close friends, but that's separate from our professional relationship.
* Focus on the professional relationship. One way to see that is when your editor leaves (and editors move around), the relationship often ends.
* You may not like this term, but you are like a salesperson. You offer a commodity (books and articles). If you leave publishing and go into another field, you probably don't stay in touch.