The HBO series returns in April 14.
During an interview with KISS Breakfast's Tom Green and Daisy Maskell on Friday, the 32-year-old actor confessed that Leslie didn't talk to him for three days after he told her how things end for his character, Jon Snow.
"I told my wife last year how it ended, and she wouldn't talk to me for about three days," he said. "And she'd asked!"
The actor -- who married Leslie last year after the pair met playing love interests on GoT (her character, Ygritte, died in season four) -- wouldn't share details of the HBO series' much-anticipated ending. Harington did say, however, that it's going to be "groundbreaking."
"I can't really answer whether I'm happy or not. I don't think it's about happy or sad really. I’m satisfied with what they did, but I don't know whether I'll be really satisfied until I see it," he expressed. "It's quite nice walking around, which will only happen for a few months before everyone's seen it, knowing. I know and no one else does. I know how it wraps up. Yeah, I think it's gonna be groundbreaking."
As for rumors that the cast will celebrate Game of Thrones' eighth and final season at the Glastonbury Festival in Somerset this June, Harington revealed that it's not the case -- at least as far as he knows.
"[Maisie Williams] just made that up!" he insisted. "Well, maybe I haven't been invited, maybe everyone's going to Glastonbury but me, this is the first I've heard of it. No, I'll be calling her after this and saying, 'What's that about then, Glastonbury wrap party? Yeah, where's my invite!'"
Williams also recently spilled on Thrones' final season, telling Sky News last month that fans might not be too happy with how the show concludes.
"I don't think anyone is going to be satisfied [when it ends]," she said. "I don't think anyone wants it to end, but I'm really proud of this final season."
Game of Thrones returns April 14 on HBO. See more in the video below.