All stats are connected, so you have to manage them all!
For example, if he's sick, his health will drop, meaning that his happiness and affection will drop as well. If his satiety is low, he will have less energy for interactions, and his affection and happiness will drop as well. There are a lot of small variables that control his mood, but if you focus on his satiety, all other stats will follow :]
And you'll be able to give him treats after a certain point in the story, but the content for this build is somewhat short, so you won't get a lot of return for giving him treats right now, so just enjoy his verbal abuse for now, the 4 or so story events currently available, and come back next month for the next build :D