Teenagers don’t exactly have the market cornered on emotional maturity. They’re still developing. So, odds are high that a teen on the autism spectrum has already had a number of uncomfortable peer-encounters by the time he or she reaches adolescence (e.g., teasing, bullying, peer-rejection, etc.).
You can see why the ability to engage in age-appropriate social interaction needed in adolescence may be the one thing that a teen with Asperger’s or HFA associates with failure.