I thought this was interesting, it never mentions Asperger's or Autism, but I think it does a good job of explaining why the social isolation of many people on the spectrum isn't necessarily about poor social skills (although it is possible that some people have an intellectual understanding of social skills but have difficulty putting them into practice) or a lack of empathy (and also why telling a lonely person to be more outgoing and go out and meet people isn't helpful; it's entirely possible to be around people all the time and have lots of social interaction but still feel lonely due to never making meaningful connections with people):
http://nymag.com/scienceofus/2015/07/why-lonely-people-stay-lonely.html
http://nymag.com/scienceofus/2015/07/why-lonely-people-stay-lonely.html