The two kept close on the carpet, with the 44-year-old This Is Us star wrapping his arm around his 31-year-old actress girlfriend. Pernas stunned in a coral gown with a thigh-high slit, but it wasn't her dress that turned heads. Fans quickly took notice of Hartley and Pernas' left hands as they were both wearing accessories on that finger.
ET has reached out to the actors' reps for comment on the marriage speculation.
Last July, Hartley spoke to ET about his life after his split from Stause.
"I'm a happy guy. I sleep like a baby. I don't have anything on my mind," he told ET at the time. "I treat people the way I want to be treated and I have lovely friends who love me and I love them. And I've got this wonderful daughter, and I've got a great family, and I am a very, very lucky, lucky individual."
Hosted by Leslie Jones, the MTV Movie & TV Awards aired from Los Angeles on Sunday at 9 p.m. ET/PT.