Beverley-born Andrea Jenkyns, who represents the seat of Morley and Outwood, is dating Army veteran Jack Lopresti, who has three children with his wife Lucy.
The pair were pictured together at Doncaster railway station in photos published by the Sun.
A statement released by the Conservatives said: “Jack and his wife discussed breaking up in June. They intended to have Christmas together as a family with their children.
“Jack and Andrea have very recently in the last few weeks begun a relationship. They would now ask for privacy.”
Soprano singer Ms Jenkyns, 41, made headlines when she narrowly beat the former Labour shadow chancellor in one of the biggest upsets in May’s election.
Before her election to Westminster she was a county councillor in Lincolnshire and worked as a secondary school music teacher and as an executive with a management training company.
Mr Lopresti, whose website states he lives in Filton, Bristol, with his wife and youngest son, entered Parliament in 2010 as MP for Filton and Bradley Stoke and has had roles on several select committees.