In a letter dated May 3 and published on Catholic websites, Bishop Dooley said:
“While there have been many blessings that come with being your bishop, it has been a particularly harrowing and testing time for me personally.”
He said he was looking forward to returning to the role “with new energy and focus”.
Vicar general Fr Gerard Aynsley would take over the bishop’s responsibilities.
Bishop Dooley had been in the post two years.
He could not be reached for comment yesterday.