The pair starred opposite one another on CBS crime drama Stalker and got engaged in early 2015
Dylan McDermott and Maggie Q have split.
Four years after the American Horror Story actor and Designated Survivor actress got engaged, the couple is going their separate ways, a source confirms to PEOPLE.
Reps for McDermott and Q have not commented.
They first sparked relationship rumors in fall 2014, when McDermott, 57, and Q, 39, were spotted getting cozy while shopping in Brentwood.
In October of that year, a show insider told PEOPLE that the Stalker castmates were romantically involved.
Just months later, the pair was engaged — he proposed after seven weeks — and Q was sporting a massive diamond on her ring finger.
One month later, Nikita star Q told PEOPLE that they were “fishing for dates” to tie the knot.
At the time, the duo was busy with their careers — including new movies in the works for both — which is why they hadn’t settled on a wedding date.
“So, yeah, [it’s] because of work,” Hawaii-born Q said in March 2015, “and … because you gotta balance everything.”
Last year, McDermott opened up to PEOPLE about his relationship with Q.
“The cool thing is if you trust life and open yourself up to good things, good things can happen,” he said. “[Maggie] took my breath away.”