What makes it interesting is that your play the good side and the bad side and it's hard to choose which side to be on because the characters are so profoundly developed that you'll find yourself empathizing with their actions and thoughts.
In the meantime, when he starts complaining respond by empathizing with his woes, you might say something like, "that's too bad" or "sounds like you're having a tough time" and then change the topic.
Although this behavior is not unique to marriages dealing with autism, adults affected by ASD have difficulty empathizing with others and understanding another's point of view.