Sophie Turner on Why Fiance Joe Jonas Had to Sign a 'Game of Thrones' NDA (Exclusive)

Turner also opened up about how she turned to therapy to deal with the identity crisis she faced with leaving 'Game of Thrones' behind.

Dying to know how Game of Thrones ends? It pays to be engaged to one of the stars!

Sophie Turner is sharing how her fiancé, musician Joe Jonas, became privy to how the final season of the HBO drama pans out. But the inside knowledge didn’t come without a non-disclosure agreement.

"Joe was on set most of the time so he kind of figured it out and he was like, 'Can you fill me [in]?'" Turner shared while talking to ET’s Leanne Aguilera at WonderCon in Anaheim, California. "And, he signed an NDN, NDA and everything so it’s all good."

The eighth and final season of the show kicks off on April 14, but Turner shared how the difficult goodbye started long ago for her.

In fact, the 23-year-old actress confessed that stepping out of the shoes of her character, Sansa Stark, for good sparked an identity crisis and it’s only thanks to therapy sessions that she has been able to deal with the life change.

"Six or seven months ago, just after Game of Thrones finished, I went through a bit of a wobble as I think everyone would when 10 years of your life is suddenly like gone and you will never be that character again," Turner shared. "I went through a bit of an identity crisis and suddenly feeling a little bit inferior. And then, you know, therapy really helped and now I kind of own everything."

Indeed, Turner is killing it post-Game of Thrones filming. In addition to her personal life at a high thanks to her upcoming wedding to Jonas, she’s also about to make her mark with her first leading role in a blockbuster film as title character in X Men: Dark Phoenix, the latest in the X-Men franchise.

The film sees Jennifer Lawrence’s character, Mystique, get killed off.

"I think her contract was up or something so she was ready to leave anyway," Turner said of being responsible for Mystique’s exit. "I just gave her a dramatic death scene. I think she was happy with it. It was fun. It's kind of nice -- it's quite an honor to be the one to kill off Mystique. She's such a beloved character, so it's kind of cool."

"We all cried when it was Jen's last scene," she added about how the farewell was such a bittersweet moment. "Everyone, especially the people that had been working on the movie for so many years. It was an emotional moment. But it was also great. We partied a lot after and we felt pretty good about it."

Of course, it’s the Game of Thrones goodbye which likely caused the most tears. Reflecting on what she will miss the most about the series and its tight-knit cast, Turner admitted "everything," before concluding that the power she felt Sansa Stark was unlike any other role.

"I think the thing I will miss the most is being in character, in costume, on these amazing sets and being with this crew of people for 12 hours a day and these other actors in their costumes as their characters," she mused. "Like being on the grounds of Winterfell as Sansa Stark -- I never felt more powerful than I have as her in Winterfell, so I’ve just never been happier on a set than Game of Thrones."

ET is in Las Vegas all this week with exclusive reporting on the biggest stars from CinemaCon, an inside look at Las Vegas’ most iconic hotspots and exclusive content from the 2019 ACM Awards. Don't miss it!

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