animals like dogs don't have the capacity of complex learning or emotion
it's more likely that you've conditioned the dog than that the dog has developed an intense emotional connection, especially if this is something that's happened multiple times. a human can be loveually assaulted and have the mental ability to say "even if that felt good i did not want it and it was not ok," because humans are obviously more intelligent. a dog can be loveually assaulted, but it doesn't have that same capacity. if it feels good, all the dog knows is that it felt good. unfortunately, it's extremely unlikely that the dog realistically developed a love-like emotional connection, rather, through positive reinforcement, the dog is now conditioned to receive the treatment.
that being said, bestiality is certainly a moral issue and i don't really have any business saying you're "wrong," but i do have business in explaining that creatures of the intelligence of a dog simply don't have human-like emotion or thought capability to "give consent" in a meaningful sense, nor do they have a sense of complex morality, including loveual conduct. the gestures you're observing may be perceivable as a form of consent, however the conditioning itself which led to the situation wherein the gestures occur was likely done without such signals.