Marteen- completely and 100% on point (for me at least) when you say detachment is difficult to master- incredibly difficult for me. Because I think as codies we tend to see our own personal identity in relation to another and our own worth as based on how THEY are treating us, detachment occurs when we can actually practice separating ourselves from others and taking back our power.
I also think to a large degree it has to do with trusting ourselves- when we can trust ourselves as being real and our feelings valid we can begin to own our own power.