Lady Gaga and Taylor Kinney's careers have been blamed for their split.

A source told PEOPLE: "Their work kept them apart a lot. 'Chicago Fire' keeps him in Chicago and her work is almost always elsewhere."

The pair haven't been pictured together recently and she hasn't shared a picture of him on her social media accounts for over a month.

Last week, on Taylor's 35th birthday, Gaga, 30, was seen without her engagement ring while she was out and about in Malibu.

Taylor and Gaga met on the set of her 'You and I' video and she previously revealed how they kept their long-distance romance alive.

She said: "We don't have any rules about calling each other at certain times ... We'll go days at a time without talking and then we'll talk every day. He's on his journey and I'm on mine and we're gypsies. And then when we're together, we're really in love and that's it."

And she explained that her mother Cindy was in charge of planning the nuptials.

She said: "I think if I wouldn't let my mom do this with all of us and my family - I think if I would've denied the women of my life the planning of the wedding - they would probably kill me. I have all the help in the world in a way!"

The 'Born This Way' hitmaker was adamant her wedding to actor Taylor was going to be low-key.

She added: "We are not planning anything that is worth writing about."