This Is Us is a comforting melodrama that sandwiches its most heartbreaking moments in between its most heartwarming ones. A happy family Christmas can be ruined by tragedy; the joy of finding unknown relatives is marred by fatal disease. In its effort to simulate the ups and downs of real life (albeit with a more exaggerated tone), This Is Us gives its viewers the good with the bad. That's never more clear than with Jack, the perfect patriarch whose days are numbered. Jack's upcoming death has been woven throughout the first season, but the show hasn't yet revealed just how he died. These This Is Us theories about Jack's death explore the possibilities.
Details about Jack's death have emerged over time, but they are few and far between. Viewers know that his children are still coming to terms with what happened even though it's been many years later; the memory of their father still affects them on a day to day basis even if they don't talk about him all the time. As the episodes go on, the show gets closer and closer to explaining the circumstances surrounding his death, but until it reveals everything fans can only guess at what happened. Here are a few potential explanations.
When Toby had a heart trouble during "Last Christmas," it seemed to stir up deeply anxious feelings in Kate, so much so that she was particularly insistent about him having surgery to aid his recovery. While that could have just been because the man she loved was in danger, fans were quick to point out that it may have stirred up bad memories. Perhaps Jack died of a heart attack and Kate's resultant anxiety about Toby was motivated in part by her past experiences with her dad. It wouldn't be the first time Jack's presence has had an effect on Kate's current relationship with Toby.
Another theory that some fans have put forth is that Jack died during the terrorist attacks on 9/11. That could explain why both Kate and Kevin are skittish on planes, and why Kevin threw out all of this model planes after Jack died. It would also fit with Jack's personality for him to rush to help out during a dangerous situation. However, the timeline might not match up. The kids appeared to be teenagers when they were shown at Jack's funeral, but if he died during 9/11 then they would likely have been in their early twenties. Still, it is a possibility; the glimpses of the kids caught during the funeral were far from clear.
So far the only flaw Jack has been shown to have is the drinking that momentarily caused friction between him and Rebecca when the kids were young. While he promised to clean up his act (and appeared to follow through on that promise in subsequent episodes), there's no telling what happened in the intervening years. Jack may have fallen off the wagon and his death could have been due to some alcohol-related issue.
Though This Is Us has been slowly revealing more about Jack's death, don't expect to get all the details anytime soon. In some ways, that's a good thing. While it prolongs the mystery, it also puts off the inevitable; the longer the show goes without explaining it, the longer the audience can put off having to deal with the reality of Jack's death. Until then, everyone can just live in denial and pretend he's still alive — I know that's what I'll be doing.