Valentine's Day is almost over and I was in a rush to submit my story and my contribution to this kind of romance this year. For now here are a couple of stories that fit this thread.
My very rough draft Tailmon/Gatomon TF story about a Tailmon gifting her tamer with the power to transform.
https://www.furaffinity.net/view/35049178/
Lycandope's Leashed story series count especially in the last chapter.
https://www.furaffinity.net/view/29128697/
https://www.furaffinity.net/view/30832246/
https://www.furaffinity.net/view/34691942/
Now this is a quick one that I want to point out. This author made a story series about a guy who starts dating shapeshifting witch who likes to transform herself and change reality so no one would think it's strange.
Anthro Cow
http://www.furaffinity.net/view/32996367/
Anthro Snake:
https://www.furaffinity.net/view/33053889/
Anthro Elephant:
https://www.furaffinity.net/view/33732232/
That's it for now, the rest will come later.