Well I would guess this is about each of your attachment styles, rather than, or aswell as, autism. This is the style of attaching to others and relating that we develop in childhood, some develop secure styles, where others don't always get enough reassurance to feel wholly secure, and develop insecure styles.
Of the insecure styles, and probably due to gender conditioning about how we should express ourselves, its relatively more common for females to develop a style called Preoccupied where they may cling and come forward anxiously, and for males to develop a style called Dismissive. However both styles are based on anxieties, and are just ways the person has found to manage anxiety. He is distancing to manage anxiety, probably, and you are doing the opposite and clinging.
These two insecure styles are fairly common, and autism probably complicates things too. In effect, when something difficult occurs, the way each of you manages anxiety will have an effect that's difficult for the other, unfortunately. It is good to get support for yourself from other sources, like coming here, but also reaching out to friends or therapist, to help you with your anxiety. Then you can help him by not pressuring him. When you feel calmer and supported, you can just let him know you are doing that and are there for him if wanted.