This Is Us spoilers: Will Jack and Rebecca's marriage fail? Showrunner teases intense last episodes

Jack showed the first signs of a not-so-perfect husband, Kevin followed his heart and did exactly what his father would have done and Kate got kicked out of her weight-loss camp. This Is Us episode 15 titled Jack Pearson's Son was not your usual melodramatic episode. Instead the NBC show unveiled the flaws of the beloved characters especially of the dreamy couple – Jack and Rebecca.

Tuesday's episode (click here to watch online) revealed a different side of Jack when his unwavering support towards his wife's dreams seemed to fade off as she joined her jazz band for a five-state music tour. In an explosive moment, he even confessed his true-feelings to Miguel.

"How the hell is she going on tour? I mean, I could deal with the piano bar a couple nights a week, but a tour? I mean, who does she think she is, Janice Freakin' Joplin?" an exasperated Jack said in the episode. Soon after this explosion, the ever-romantic couple ended up with a huge fight and an even worse Valentine's Day.

Is this the first hint of wears and tears in Jack and Rebecca's marriage? In a recent interview, showrunner Dan Fogelman teased the couple' future and warned fans about "pretty intense" last few episodes.

Spoiler alert: Proceed at your own risk

"Jack's going to be acting as the sole nurturer caretaker of the kids once she's gone for a little," Fogelman explains before revealing Rebecca's struggles. She "is battling both nerves and 'Am I doing an okay thing by my family to be leaving them right now?' Jack tries to strike that balance between being supportive, but is also really uneasy with some of the aspects of this."

While Jack and Rebecca battle a tough time in their marriage, in the flash-forward Kevin appeared to be a bundle of nerves with the approaching opening night of his play. Despite investing a great deal in the play, ultimately Kevin prioritised his family as he bailed at the last moment to be by his brother's side.

"We follow [Kevin on] the day of, as he battles nerves and looks for guidance to calm his nerves — and finds it in a most unexpected place," Fogelman said hinting at the surprise change in Miguel and his step son's relationship.

In short, Fogelman concludes that the final few episodes will be "heavy duty". "The end of [last week's episode] is the hinge of the rest of the season, and people just need to buckle up for the last four episodes — because it's going to be pretty intense," he sums up.