@AnnaSaultron I think the context matters, romantic relationships (unless there is a kink involved or an irregular situation) can't be categorized as a pet ownership situation. Often two consenting adults in a romantic relationship can fulfill their daily survival needs, possess agency in what happens to them in daily life, navigate interpersonal situations, can give or rescind consent in a meaningful way.
Pets in a captive situation cannot do some of these things, they are often at the whims of their owners. Sure, pets can communicate to an extent with their people and others, it's very limited. There is certainly an element of affection in an owner/pet situation, but it's a very platonic kind of social connection. Pets don't get the luxury of agency like people; owners make decisions for their pets which they don't have any power to change.
Based on my impressions from reading about how AI/human relations go on spaceships...The AI helps them with a lot of tasks humans find impossible, might have a sense of affection for these fleshy creatures existing within the confines of the physical place it's housed. If the AI has control over what humans might do day to day and influences their actions in ways that a pet owner would...Humans might be considered pets in that particular situation.
BTW; this is me trying to process my gut feelings on this matter and communicate them in a way which might be considered coherent...I might be wrong!