'This Is Us' ' Chrissy Metz and Chris Sullivan Hint at 'Secrets' Affecting Kate and Toby's Marriage

"Real intimacy is trust and so there's a bit of trust that's broken," Chrissy Metz tells PEOPLE

Published on October 1, 2019 10:00 PM

For This Is Us‘ Kate and Toby, being first-time parents is uncharted territory.

As they move into their new home in Los Angeles and learn pro tips about raising sight-impaired son Jack, who is now 187 days old, the pair faces a challenging time in their relationship.

And Chrissy Metz tells PEOPLE that not only will Jack’s blindness affect Kate and Toby in the present day, but, as fans have already witnessed in episode 2, both new mom and dad display different coping mechanisms that may affect the fate of their future together.

“I did learn about how, instead of, of course saying, ‘Oh, look at this,’ you have to narrate what’s going on,” Metz, 39, says of applying what she researched into her role as baby Jack’s parent. “We sort of take for granted when a child is able to see. Then with a child who’s seeing impaired, there are times where people are like, ‘Oh, Jack look at this.’ You just forget.”

The actress adds, “The real baby is not seeing impaired. So it’s really about training your mind to narrate, or before something happens, to make sure that you’re explaining what’s going to happen as to not surprise the baby.”

Metz’s on-screen husband Chris Sullivan describes a “fun” environment on set, much to the contrary of his character’s experience thus far as a dad.

“Once we got the hang of it, everything seemed to kind of fall into place. The babies that we’re working with are great, and they’re actually very easy,” he says before jokingly making a reference to Kate and Toby’s dog, Audio: “It’s easier than working with the puppy.”

Fans saw Kate putting on a brave face as she navigates parenthood and the realities that her son will grow up with a disability. Though she makes an endearing speech about living a life without limits, Kate, in turn, appears to be limiting herself from expressing her worries and stresses.

“I think Kate doesn’t want to admit that … not that it was her fault in any regard, but that she feels responsible,” Metz explains. “So, being that vulnerable with her husband and, of course, her mom — they have a layered past — she always feels like she’s a bit inadequate.”

Though Kate’s guard is up around husband Toby, who has put his wife at the top of his list of things to be concerned over, and mom Rebecca, Kate finds solace in twin brother Kevin (Justin Hartley).

“Kevin is her safe space because they are twins and they share the most difficult parts of their lives together, without judgment and with love,” Metz says of Kate opening up to her sibling about Jack’s first six months. “I thought that scene was so beautiful and important. They both have been going through their own thing, so it’s great to see them come back together at such a difficult time.”

Amid the ups and downs, Kate slips back into overeating to cope with her day-to-day, while Toby uses working out as his stress relief — and everyone notices the results. The father of one has been going to the gym behind his wife’s back and lying about his weight loss to the family, blaming his trim figure on the pressures of raising a newborn.

And Metz foreshadows tension between Kate and Toby in the near future.

“I don’t think that fans will necessarily expect the secrets that Toby was keeping and how that’ll affect their relationship and moving forward,” she teases.

“Trust really is intimacy. The physical stuff is great and wonderful, but real intimacy is trust and so there’s a bit of trust that’s broken in him keeping this weight loss and working out a secret. We’ll see how that evolves and unfolds with them,” Metz adds.

Meanwhile, Sullivan, 39, references his character’s previous heart attack and depression, and hints: “As of right now, it seems like Toby’s figured out where his priorities are, and his priorities are staying alive as long as possible for his son.”

“As we’re coming into the fourth season, it becomes a real conversation about what we do with the time that we have,” he says. “I think the thing that Toby has learned up until episode two is that we don’t have that much time.”

Fans continue to replay that ominous flashforward during the season 3 finale — of which an eighty-something Rebecca appears on her death bed — when a much older Toby, who isn’t wearing his wedding ring, tells family members: “I just talked to Jack” — now a successful singer expecting his first child with wife Lucy — “and they’re on their way.”

The “they’re” prompts questions such as: “Are Kate and Toby still married?” and “Does ‘they’re’ mean Jack and pregnant Lucy?” or even “Is Kate still alive?”

This Is Us airs Tuesdays (9 p.m. ET) on NBC.