Most readers either have pets or fond memories of them. Seeing a heroine who is a "cat momma" or a hero who spoils his loyal basset hound makes the characters feel like real people with lives outside of their romantic pining. These small details make your book's world feel familiar and lived-in.
Certain species engage in behaviors that seem to strengthen their pair bonds. For example, many bird species are known to engage in elaborate courtship rituals. Wwwsex con anial