Take The Black Stallion and its lesser-known sequels focusing on the girl, Alec’s friend. Or, more directly, Anna Sewell’s Black Beauty , narrated by the horse, but experienced through the women who love and lose him. However, the most potent modern example is Merida in Pixar’s Brave . While Brave is subverts the traditional romance arc (Merida rejects suitors), her relationship with her horse, Angus, is the emotional core. She tells Angus her frustrations about her mother and the suitor games. The horse doesn’t answer, but he doesn’t judge. He runs with her, sharing her wild longing for freedom.
Louisa May Alcott’s Little Women provides a devastating example. When Jo March sells her beautiful, long chestnut hair (not an animal, but a "mane" of wild, animalistic femininity) to send her father money, and then later, when she chooses to leave behind her wild scribbling and Beth’s kittens, she is slowly losing her animal self to become a wife. The quintessential animal-loss-romance moment, however, is in The Bridge to Terabithia (though more tragic than romantic). Jess’s connection to the natural world and the imaginary beasts of Terabithia dies with Leslie.
Consider The Parent Trap (1998). The villainous fiancée, Meredith, has a tiny, nervous Chihuahua that she treats as an accessory. The dog is not a character; it is a prop. Contrast this with the twins’ connection to their grandfather’s Labrador or their father’s horse. The audience immediately understands that Meredith is unworthy of the father’s love because she sees animals as things, not beings.