A source close to the couple said: 'Taylor has told her she's married to her career and he can't deal with dating Gaga the megastar and all her obsessions and alter-egos.'
The source adds: 'He loves the cool down-to-earth girl but hardly gets to see her. Gaga never stops working - she writes songs in the shower and dreams up new outfits in her sleep.'
The Chicago Fire actor is apparently frustrated by how little time he gets to spend with the singer. The couple have not been pictured together since August and the singer is said to be constantly preoccupied with her work during the moments they are able to steal away.
Gaga is known for her fierce work ethic and it is not the first time that her popstardom has gotten in the way of romance. She shared her struggles with fans by tweeting lyrics to her new song 'I wanna be with you.' Gaga wrote: 'Wish I could have both, but I can't on the road.'
Speculation has been fuelled by reports that Taylor has grown close with his Chicago Fire co-star Brittany Curran. Brittany took a snap of herself and Taylor watching a Red Sox baseball game last week.
Despite her success in the charts and the release of her new album, Artpop, Gaga has had a less momentous year in her personal life. The star grieved the loss of her dog after receiving surgery on her hip earlier this year. The split will be yet another set back for the quirky singer.
It would seem that Lady Gaga has been unlucky in love again and it might be farewell to another Mr Gaga!