Some writers create variations and twists on an appealing relationship that is their personal signature, some pair up their characters and then let their quirks determine what their relationship looks like, resulting in happy couples who are great for each other but maybe not for anyone else.
Both are great, an example of this would be the difference between Nalini Singh books and Kresley Cole books

This list is for me to track writers that do the second thing and write unique couples with specific relationship dynamics.

Including just the first of a series