This is actually more what I'm driving at in this post but it struck me as more point B, and I thought really it would be best to start with point A. I think once you reach a place of not placing expectation (and subsequently deriving either elation or disappointment depending on the result) on an interaction, and once you rank your own self valuation above whatever others might say, you become extremely stable from an emotional perspective. Somebody can think you are amazing or someone can think you ain't squat and it won't matter really because your internal self worth is what matters and that is the valuation that you default to.
From that place something pretty neat happens. You can accept people into your life whose values line up with your own, and whose opinion of you lines up with your own, but you are then selecting from a place of awareness and congruence (internal validation or self-validation), not from a place of "OMG! She LIKES me! I must be likable!" (external validation) The issue I think some wrestle with from the outside looking in is that to the outside observer it is impossible to tell on the surface who comes from a place of internal versus external validation. And its important because for those that are learning in life it is much better to have internal validation modeled for you.
With regard to relationships, and love relationships in particular, the internal validation gives you the power of choice. I think at point A, as I tried to describe in the OP, emotional detachment is necessary because at that juncture a person is much too attached and emotionally dependent on the external stimuli. The external stimuli is affecting internal value asssignment, and therefore detachment is necessary and best. However, once one has progressed to a more well formed self-image and one has arrived at the ability to be strong in sense of self and internally validated, then the emotional detachment does a disservice.
An internally validated person chooses to love, chooses to invest, chooses to give time and emotional energy to a relationship out of a stability and generosity of spirit. It is an outpouring of abundance and an overflowing of internal self love. The giver gives without expectation and because of desire. The internally validated person chooses to make the emotional investment in someone else from a position of choice and strength and desire only, never from need. There is not withholding out of fear (although there is awareness that the emotional investment may or may not be fully reciprocated), and there is not numbness to emotion either. You open yourself willingly to rejection and to disappointment, but if rejection or disappointment occur, it cannot wreck who you are internally because you are already internally validated, and another individual's shortcomings and issues are not internalized to you.
I for one seek joy in relationship. In order to experience joy the ideal is for two people to love, respect, appreciate and support one another through life's journey. It doesn't mean everything is always unicorns and rainbows, but it is true partnership and companionship and fulfillment. Its what I would wish each of you to manifest in your own lives. For joy to manifest itself, I think (because I've not reached that point yet in relationship) it takes two emotionally mature internally validated people who are enjoying one another and giving freely to one another. I came closest to this with a lover that faded a few months ago after nearly two years. He faded not because of me or anything I did or didn't do, but because of other obligations and stresses in his own life, and because I realize it wasn't me at all, I am grateful for having been a place of light and joy for him while he traversed a tough road in his own life. I chose to love him without expectation and I found the experience to be lovely, although relatively short lived. That is to me what love and joy and abundance are really about. And people who are capable of this are hard to find. So I hope this thread casts some light on where it is good to aim because as we all progress along the path I trust that we also begin to recognize the same characteristics in others, and begin to see with new eyes.