If you have the trait Tight Bonds, you swap it for this trait at the moment you decide to betray the relationship. (You need not wait until you have actually committed an act of betrayal.)
It is possible to regain the Tight Bonds trait, for either the same or a different relationship, but it requires substantial in-character work. The GM decides when this trait reverts back to the original one.
Pathfinder Player Companion: Cohorts and Companions © 2015, Paizo Inc.; Authors: Brian Duckwitz, Philip Minchin, and Jason Nelson.