The "Dip It Low" hitmaker had been linked to the rapper since last summer and after playing coy for months, she confirmed the rumours in May, reported Us magazine.
"They've broken up a few times before. She's got so much going on with Grandfathered, her E! and Hulu shows, and working on her album with Wayne. It doesn't help that Wayne is all over the place too. They both have insane lives and schedules," a source said.
Milian, 33, who showed off a tattoo of the acronym TNT, which stands for Tina N' Tunechi - Wayne's nickname - earlier this year (15), previously gushed about her relationship with the hip-hop star.
Milian previously dated Mariah Carey's ex-husband Nick Cannon and was married to music producer The-Dream, while Wayne, 32, was previously engaged to The-Dream's first wife, R&B singer Nivea.