Mae Whitman and Craig T. Nelson Mae Whitman and Craig T. Nelson

Yes, Parenthood fans. Mae Whitman is well aware of that super spoilery promo NBC unveiled last month for the show's upcoming final season. But she's still pleading the fifth about what's ahead.

"I still can confirm nothing and deny everything," she tells "I know the feeling of getting a spoiler that ruins something that you really truly love and I think it's one of the most horrible things that you can do to someone."

After six seasons starring on one of TV's most beloved dramas, keeping upcoming story lines under wraps has become old hat for Whitman. Sadly for the show's loyal fan base, she won't have to worry about that much longer. Parenthood kicks off its sixth and final season on Thursday at 10/9c. "That's one really great part about all of this is that we are able to say goodbye," she says. "I think we've built up these people that everyone cares about and you want to know what's going to happen with them and at least feel like there's some sort of wrapping up of your long life with them."

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That's particularly true for Whitman's character, Amber, who ended last season at a major crossroads. After her ex-fiancée Ryan (Matt Lauria) returned from Afghanistan severely injured, Amber rushed to the hospital to be by his side. Although they shared an emotional, albeit awkward, hospital bed rendezvous — that may or may not have produced a child — the lovebirds ultimately went their separate ways. "I can't believe I'm saying this, but it reminds me of a Taylor Swift lyric where she says, 'I forget about you long enough to forget why I needed you,' and I've always loved that," Whitman says. "It was the first time with Ryan and Amber that you really felt this really raw display of love, but also that they weren't what was best for each other at that point. ... It was a really hard and special scene to play."

It was also a sign of great maturity for Amber, a character who's come a long way since the series debuted. Back then, Amber was only 16 years old and a "literally petulant being," Whitman recalls. "Something I loved about this character since the beginning was that you get to follow her through this strange of period of adolescence into adulthood. It's a really difficult transition and I feel like I struggled with it in a big way and I feel like it's not something you get to see on TV. ... Like in life, it is two steps forward and one step back with her."

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However, Amber made the biggest leap in Season 4 when she met Ryan. Although Whitman's performance had been earning praise since the series' inception, it was when her character fell in love with the quiet yet sweet army vet that she earned some of the best reviews of her career. The on-screen relationship helped Amber graduate from the kids table once and for all. "[He] really gave her a sense of strong, confident, supportive love and appreciated her for all of the things that he wasn't and she did the same. I think they really taught each other about balance and what a healthy, loving relationship can be even if it's not one that can necessarily sustain," Whitman says. "They really went through a real journey and taught each other how to grow up. I was appreciative that [the writers] took her on that kind of a journey. I think she really came out of that as a much more mature, balanced, stable woman."

Even showrunner Jason Katims is amazed by how far the character has come. "Amber is one character that's a big surprise to me," he says. "She's in a completely different stage of life than she was at the beginning. I didn't see that coming when I was starting the show."

The rollercoaster on-and-off relationship between Amber and Ryan, or "Ryber" as they are affectionately known among fans, also cemented Whitman's status as one of the best criers on TV — an honor she's "extremely flattered" by, thank you very much. "Sometimes I get it negatively, and people are like, 'Amber cries too much,'" Whitman says. "I'm not getting those scripts and going, 'I'll cry in this scene and then I'll not cry in this scene.' When you love someone as much as I love Lauren Graham and she's looking at you with those baby blue eyes and they start to well up with tears, there's just no way around crying."

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Although Whitman hopes Amber's ending is slightly less emotional — "I would like people to know that she's going to be OK," says the actress, it sounds like there will still be plenty of tears off-screen when the cameras stop rolling. "I've never been on a job where I've almost been more stressed about not being able to see all the people that I get to see every day," says Whitman, who counts her TV mom Graham, as well as her on-screen brother Miles Heizer, as two of her real-life BFFs (see: Exhibit A). "I've been working since I was a little kid and I've never experienced a set like this."

Although Whitman says she wishes she "could do this show for the next million years and watch [the characters] grow old together," she knows it's time for it to end. "It will be good to let them go and live their imaginary lives for the rest of time. But it's definitely going to be hard and sad." For Parenthood, we wouldn't expect anything else.

Parenthood's final season kicks off on Thursday at 10/9c on NBC.

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