What are examples of reasons why duals can end up distant from each other?
Initial lack of attraction is "normal" within the theory, and we already know how that works (opposing clubs, etc.). What I'm more interested in is what can happen after a relationship / friendship is already begun, particularly if it's a long-standing one. We've had tons of dual-related threads (it is a huge motivator behind the development of the theory, after all), but I don't remember seeing one focused on this aspect.
Preferably share real life examples and stories, but theoretical ones are ok, too. And I do want to know NTR factors. So if you know of a failed dual relationship, describe it here. Feed me data, please.