Sometimes people with Asperger's can feel overwhelmed by too much interaction or too much going on throughout the day. They will then engage in techniques or methods of their own to self-soothe or ground themselves. This will most likely involve ignoring you, (maybe even just telling you to go away or making it clear that they need time on their own), and doing whatever it is they need to do to relax. Many people do this to avoid a meltdown, whatever their version of a meltdown might happen to be. The main thing to understand here is that although at times we all get that feeling of having 'just had enough' or reached the limit of how much stress and how many people we can deal with, someone on the spectrum might have a much lower threshold for this type of thing.
I can elaborate and give examples if that would help. To a certain extent I am just generalizing based on people I know, so it would be helpful for others to add their points of view and experiences. Overall, you will have more success trying to understand his point of view, and changing your behaviour, rather than trying to make him just be 'normal'. Relationships are about give and take, but he struggles in ways that you don't, and his general self-awareness, and ability to see someone else's point of view may not be as good as yours.
