'This Is Us' Reveals Heartbreaking Reason Why Miguel Is Absent in the Future

The latest episode put the spotlight squarely on Miguel, giving insight into his family background and eventual end.

Spoiler alert! Do not proceed if you have not watched Tuesday's episode of This Is Us.

Miguel Rivas took center stage in the latest episode of This Is Us, which revealed the heartbreaking reason why he wasn't by Rebecca's bedside on her last day in the far-off future.

Simply titled "Miguel," the hour was dedicated to his story -- from his days growing up as a kid in Puerto Rico to the fracturing of his family to his last years caring for Rebecca -- filling in many of the blanks and answering a bevy of questions people have had over the last six seasons. Viewers will recall that Miguel was one of the prominent family members missing in the future flash-forward as everyone gathered at Kevin's home to say goodbye to Rebecca. Now, we have the devastating reason why.

Signs that Miguel wasn't doing well as he got older in age were apparent in recent episodes, most notably the ones during Kate and Phillip's wedding, and only continued to worsen as Rebecca's mental state deteriorated and his own health issues became worrisome. But Miguel prioritized Rebecca's care, sidelining his own well-being (i.e. high blood pressure, fatigue, heart problems) to ensure that she would live out her last years comfortably, as he took on the primary caregiver role quite literally. He took it upon himself to do everything, from making sure he was always up at 6:45 a.m. every morning so he would be the first thing she'd see to sorting out her various medications, even though there was a hired nurse who was qualified to do all those things. 

However, it became clear that this arrangement wasn't going to be sustainable. Late one evening, Miguel found Rebecca -- wearing nothing but thin pajamas -- playing outside in the winter snow with child-like wonder. Worried that she would get sick, he raced down to get her back inside Kevin's house. As he tried to bring Rebecca back into the warmth, Miguel suffered a bad fall and ended up injuring his back, of which the side effects he felt for quite some time. As he walked past the room, Kevin saw Miguel checking on his injury in the mirror and noticed large bruising on his back, which prompted him, Kate and Randall to sit him down for a frank conversation about the future.

"We think it's time to get full-time help for her," Kate opened the discussion, which wasn't received well by Miguel: "She has full-time help."

"We're talking about permanent, around-the-clock care to help you," Randall calmly explained. But Miguel, who had been in the trenches with Rebecca from Day 1 as her memory worsened, argued that the notion of hired help isn't an "easy" solution as "she doesn't respond well to strangers."

Randall asked what Miguel would've done had he became immobile or his fall was even more severe than it was. But Miguel maintained he wasn't "seriously injured." "She's my wife! I made a vow," he fired back, some of his pride showing. "I have failed at everything else in my life. My parents, [ex-wife] Shelly. I haven't seen my son in five years... I am not leaving her side, OK? Every morning at 6:45 I am the first thing she sees when she wakes up. And it grounds her. It grounds me. So as long as she needs me, I'm not going anywhere."

Ron Batzdorff/NBC

But Randall explained that they weren't punishing Miguel. "We're not doing this to you. We're doing this for you," he said. "You've honored your vows. You have honored them and then some. We're grateful to you. We love you."

"I have to be there for her," he continued to maintain. Randall assured him he has: "You have been. You will be. Now will you let somebody take care of you now? Please?" And finally, Miguel agreed.

Even with a full-time care nurse now looking after Rebecca and Miguel, other health issues continued to crop up for Miguel as he got older. And he continued to help Rebecca with her morning routine, but this time, Kevin was there as well to offer assistance.

One day, Kevin paid a visit to Miguel's estranged son and gave him some heartbreaking information about the severity of his declining health. "Your father may not have a lot time left. The doctors are worried about heart failure and take it from me, you don't want to leave things unfinished," Kevin advised him.

"What do you expect me to do with that?" Miguel's son asked. "You do whatever you want. Thought you should know," Kevin answered before leaving.

More time passed before it was Christmastime and everyone (and we mean everyone!), was happily celebrating the holidays. And the camera panned to reveal that Miguel's son and his family made it to the get-together, implying that the issues and conflicts between father and son were in the past.

The entire Pearson clan gathered outside in front of the cabin to enjoy the fresh air, with Miguel and Rebecca standing by the large bare-branched tree. As everyone's kids happily reported their treasured finds, Miguel and Rebecca took a moment to admire the simplicity of the leafless tree.

But as the scene changed, the tree was now seen fully in bloom -- a sign that the seasons had changed. But, Rebecca was revealed to be alone in her wheelchair and wearing all black, along with Kevin, Kate and Randall, as well as Miguel's son. They had just attended Miguel's funeral. 

Amid a flashback to one of Miguel and Rebecca's early conversations where she asks him, "Who the hell are you? What's your story?," Miguel's ashes are spread at the foot of the tree by the family cabin and on the same grassy field he played at as a child in Puerto Rico. Perhaps a response to the question he's chased all his life. Back to the scene with Rebecca at the bar, Miguel answers her in Spanish before translating for her (and the audience): "I don't know, but it's a good question. Ask me again later."

This Is Us airs Tuesdays at 9 p.m. ET/PT on NBC.

To stay up to date on breaking TV news, sign up for ET's daily newsletter.