Triangulation is controlling a two-person dynamic by importing a third: the ex who 'still wants them,' the sibling who's 'doing better than you,' the friend who 'agrees with me about you.' The third point creates competition, jealousy, and self-doubt — pressure applied without a single direct demand.
Refuse the triangle, not just the fight: 'If someone has a concern, they can tell me directly.' Verify claims at the source when it matters, and notice how often the quoted jury turns out to be no one at all.