It is not a personality disorder per se though can develop into one. It's totally developmental trauma - prenatal to 3 the basis on which all subsequent relationships are then built. 99% of all psychological issues stem from disconnects and traumas during these years, those with attachment disorders suffer from this in the worst way since they never were able to internalize love at this vital stages which sets them up for every pit-fall that comes their way -from self-image to self-sabotage, to addiction to living a life devoid of human contact on one end of the spectrum to sociopathic tendencies that manifest as seeking out negative connections with the world.

And so, again am asking if you can open a new category for this please - it's well-deserved and probably way overdue as well. BTW - not all attachment disorders are Reactive.

https://internal.psychology.illinois.edu/~rcfraley/attachment.htm