My mom said that Dad got really grumpy and mean on chemo.
I think he just frequently lost his patience, and also didn't care about the stuff that he thought was little and minuscule in the grand scheme of things, stuff that is more important to people not facing the life and death and sick issues that a chemo patients have to deal with just to get through. I did see him get annoyed more easily, he just didn't want to be bothered, and mom, also being older, is pretty needy.