The basic idea is quite simple. You discover who you are by enduring pain! You are in a close relationship and things get difficult. If you stay with "it" and do not escape, either to your partner by dissolving yourself, or out of relationship, then you will be forced to get to your core self and find who you are! Fascinating idea! From my experience, this can be much more painful than it sounds. But for me, who have been on the search for a way of finding my essense, this seems worth trying.
It is inevitable and necessary that intimacy occur without trust and affirmation from your partner. Other-validated intimacy is nice when you can get it. But when you don't, you can attempt to rise to the occasion and validate yourself. Trying---and succeeding---to validate yourself when your partner does not validate you isn't as improbable as it might seem. In Chapter 12, we'll discuss how infants by age three months do the equivalent process for themselves. Being out of synch with their caregiver stimulates their ability to regulate their own emotional equilibrium. This forces you to draw upon what is solid within yourself. Intimacy involves your ``relationship with yourself'' as well as your relationship with your partner. If you're strong enough (sufficiently differentiated) to master your own anxieties and maintain your position, you will feel better about yourself. This is self-validated intimacy, which is part of the process of increasing your differentiation. In other words, it's a circular process: differentiation is both the basis for, and the result of, self-validated intimacy. Self-validated intimacy is the means to two ends: becoming more of a person and developing a more resilient intimate relationship. ---p.119, Passionate Marriage