Roma said it had been an honour to play and manage the Blues but left his post due to commitments outside of the club.
It is understood that a busy home life and work as a teacher have made it an increasingly difficult juggling act for Roma.
A club statement confirmed Richard Kane and the board had “reluctantly accepted” Roma and Martin Foster’s resignations.
Roma said: “It is obviously with a heavy heart I make the decision to step down with immediate effect from my role as manager at Gainsborough Trinity Football Club.
“For a long time this football club, this town has been a part of my life, I at this moment in time, just cannot give every aspect of my life the attention it deserves and something just had to give.
“It has been an honour and a privilege to pull on the shirt and to manage this fantastic club and although I am disappointed results and performances have not always been to the standard I would have hoped, it is not for want of trying.
“I wish the chairman, the board, the club and the supporters every success for the future, and I genuinely mean it when I say the Gainsborough results will be the first I look for on a Saturday afternoon.”
Roma, who clocked up his 200th league appearance as a player for the club in January, was appointed full time manager in the summer after a stint as caretaker towards the end of last season.
The announcement of their resignations came just 24 hours after Gainsborough’s home defeat to Alfreton Town.
Trinity have moved quickly to place Adam Quinn and Matt Wilson in temporary charge of first team matters ahead of the team’s trip to Bradford Park Avenue on Saturday (February 11).
A club statement added: “All associated with the football club would like to wish Dom and Martin all the best for the future and thank them for all of their work assembling a bright young side that hopefully the new manager will be able to mould and evolve into a more consistent National League North outfit.”