Jon woke up at her stallion's voice. She didn't want to, but making her stallion happy was more important. The sex they had last night was phenominal and Jon secretly hoped that she had concieved and was carrying a foal in her womb. A mare's maternal instinct was strong, far stronger than that possessed by human females, one of the reasons centaurs married and began having foals young. Jon and Karyn were engaged and were planning to be married shortly after they graduated from high school, but Jon figured there was no harm in being with child when they did so long as they gave their baby a loving home.
Jon, as per Karyn's wish, thought that she had always been a female centaur and that Karyn was her stallion. One of the side effects was that both of them were completely nude and unashamed of it. Centaur nudity was normal and Jon didn't understand humankind's obsession with clothes and why they bothered to cover their bodies. A female's body was beautiful and should be shown off and enjoyed, Jon thought. Jon particularly loved her breasts; even the weight and bouncing was erotic and beautiful and she didn't understand why human women would feel the need to cover them with clothing and support them with bras. Jon looked around her as the two of them walked to school. Humans and centaurs lived side by side and, while their history together had not always been easy, they had come to a comfortable detante, if not true peace and equality.
In addition to other differences, mares made up 75% of the centaur population, with stallions making up the other 25%. This allowed stallions to have a multiple mare harem, though custom dictated that a stallion have no more mares than he could affort to take care of. Mares accepted and enjoyed this arrangement as much as stallions did, not least of which because it helped to ensure that mares had girlfriends in addition to their normal friends that they could be friends with. Centaur society even encouraged lesbian relationships between mares married to the same stallion. Jon was Karyn's only mare for the time being, though after they graduated and married, though that could easily change afterward.
Jon and Karyn continued on to school.