Good question!
From my general knowledge: Aspergers syndrome is a mild form of autism. Men and women can have it but it is more common in men. It probably arises from a mixture of genetics and upbringing. Classically they have difficulty picking up on other peoples feelings, and can often be quite geeky or single minded in their interests. They work well in relation to jobs which do not require much human interaction. It depends on the severity of the condition if they can form normal human relationships.
As for the sex drive, I don't know, but I would imagine that as it is a deep primal urge in the brain then it may not be affected by the reduced empathy. It is probably as variable as in normal people. I wonder if it may be more pronounced in their first relationship as this is likely to happen at a later age than usual so they may have developed a head of steam that needs to be released before they settle back to normal.
Whats your problem? - too high / normal for teenager or too little / normal for middle age