You are using too low level meat for your pet. Chunks of Boar Meat has no level requirement so it means it is used for level 1 pets. Also I suggest you if you didn’t already get into cooking, if you cook the meat it will keep their happiness longer. Fishing is really best for hunters, get fishing and cooking or at least one of them.
I will give you an example. Raw Spotted Yellowtail gives 874 health while Spotted Yellowtail (cooked version) gives 1392 health means it is better food therefore gives more happiness.
Also I do realize if you leave your pet behind and run and it dismisses by itself, pets becoming upset when you recall them. You really need to take care of your pet lol.