To quote Alicorn:

• I think I could have lived with being a member of a triad without explicit rankings; other arrangements would have been progressively less appealing and at some point I would have been necessarily skeptical that there was enough interest for both the relationship and the subsidy to persist.

So I would guess, it all depends on the situation. Are we talking about a "primary" relationship, etc. I guess that at a certain point you could, presumably, start to quetion your role and importance in the relationship.