If you're going to have one of the grandfathers requirements be 4 Hearts with your pet, then you should at least give us the ability to see how many we have with them.
...How do you even know you have 4 hearts with your pet? Is it when it says "YOUR PET LOVES YOU!"? Heck, just add an entry for your pet in the Relationship tab (since your children are added to that, as well, heh). =x
I like the idea, but why the spoiler instead of wording it differently? "Requesting pet's (cat and dog) affection level to be shown on character screen". BTW, I believe it will be added once pets become more relevant and I hope they will one day.
I suppose CA will add it later in future patches, currently you can just look at the files in the folder to find out exactly how many hearts you have with your pet.