"Their three years together just ran its course," a source connected to the pair told Just Jared. "They have so many great memories together but couldn't make it work in the end."
The source added that they, however, ended their romance in amicable way. "The break-up was amicable - there was no drama whatsoever," the source said. "Emma and Evan are even still friends!"
Meanwhile, another source told Us Weekly that things were ugly between Emma and Evan before splitting. "They had been fighting," the second source said of the couple. The insider claimed that the separation was prompted by their hectic schedules.
Emma and Evan, who both starred in season 3 and 4 of FX's "American Horror Story", started dating in 2012 after meeting on the set of the film "Adult World". The pair then got engaged in Christmas 2014.
Prior to the break-up news, the "Scream Queens" actress was last seen stepping out at The Nice Guy in West Hollywood, California on Thursday night, June 11 without her engagement ring.