The couple, who play Fiona Gallager and Toni Markovich in the popular series, "Shameless," started dating in 2011 when the show first premiered and were regularly seen together.
However on June 4, Rossum, 26, told Us Weekly about what her perfect date night would be and did not mention Moore at all during the answer.
Though Rossum normally guards her personal life pretty closely, she did open up a bit about her perfect date night in a recent interview. While she didn't mention Moore, the 26-year-old said:
"Honestly, like, a movie and Applebee's. Just keep it simple. I want to talk to you and know what you thought about the movie afterwards. Because discussing what I do and art and movies and museum exhibitions - that's one of the biggest pleasures in life is talking about things, so I just want to talk to somebody and see what they think."
The rumors gained weight after stories appeared in Page Six and Us Weekly reporting that Rossum had broken up with Moore, detailing the pair had not been seen together for a long while and that they both had failed to mention one another when asked various questions.
Rossum was previously married to Justin Siegel between 2008 and 2010. Afterwards, she dated Counting Crows Adam Duritz for one year.
In a newly posted tweet on Friday, July 5, Rossum said she was focusing on work projects.
"Hope you all had a happy and safe 4th. Back to work starting tonight on a new film called Curfew in my home state New York," Rossum posted on Twitter.
For his part, Moore has not tweeted since July 1.