In a statement on the Diocese website, Bishop John said: "To have found love again is a most wonderful thing and I feel immensely blessed."
He first met, fiancée HJ Colston about twenty years ago and the two families have been friends ever since.
Bishop John made the announcement at a conference for his clergy after sharing the news with his family.
The diocese says they will marry in the new year.
Bishop John's first wife died in 2014. They had two daughters.