Found this while looking around on (probably unsafe) smut/manga sites years ago. I posted this before with another story I was looking for and someone recognized the other, but not this one. Figured I'd ask once more just in case!

Synopsis:
A cute love story about a boy who is asked to marry the kitsune king. He refuses several times before falling in love with the kitsune who found him and finally accepting. Unfortunately, it turns out that this kitsune is not the king, as he thought, and he accidentally agreed to marry an old, fat kitsune instead. The story contains adult content including a sex scene between himself and the kitsune messenger who he loves.