Sex.......what's it been like for you?

Hi, been with my partner for 1yr 4 months now. As I've got to know him more and more I'd put my last pound on him being autistic. All of this being fine however I do want to understand it some more. I have worked with autistic children for 10 plus years however when in a relationship its so very different. 

Our relationship is good and I'm very happy. He appears happy aswell. He doesn't talk much at all about feelings full stop. 

When we first got together sex was mental, very often, trying new things. The want to please eachother was wonderful. A real connection, not just sex. This lasted a year. And it has slowly faded away. Now I know some people will say it's was honey moon period blar blar blar but I don't believe it was. 

Was the first year an act/show. Did he do what he 'thought' was correct. 

Is his sex drive actually not very high? 

He is very stressed with work right now, does anyone else's sex drive disappear when stressed and tired? 

I use sex or the release from sex as a de stress. Having sex, kissing and cuddling calms me and helps me chill. Is this the case for you? Or the opposite? 

Is he fully being himself with me and does not feel/want sex now? 

I know you can't answer the questions but if you have had any experience in this area I'd much appreciated your impact. 

Thanks