As This Is Us heads into its final season, there are many storylines that the series has to resolve. But one of the biggest questions is one that was introduced in the season 5 finale: how do Kate and Toby wind up getting divorced? A flash-forward sequence at the end of the finale revealed further that Kate would be remarrying in the future, and Toby was nowhere to be found.

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Kate and Toby have been one of the series' longest-lasting couples, as they have featured prominently in the series from its very first episode. It would be a real loss for the series to have their relationship fall apart, but there have also been many signs that this divorce might be for the best.

Good Idea: Fans Have Been Hesitant About Them From The Beginning

Kate and Toby sit at the kitchen table in This Is Us

Fans of This Is Us have been passionate about all of the main characters and relationships in the series. But while couples like Jack and Rebecca and Randall and Beth have always been crowd-pleasers, Kate and Toby's relationship was initially rejected by fans before it eventually won them over.

Many felt Toby was too aggressive and overbearing from the very beginning, and that his over-confidence wasn't a good fit for someone like Kate as she navigated her struggles with her body image and health alike.

Mistake: They've Been Through A Lot Together

Toby touches Kate's forehead in the hospital in This Is Us

From the moment Kate and Toby met, it was clear that they both had a lot of baggage. But during their time together, the couple has endured many ups and downs, most of which they likely wouldn't have been able to handle on their own.

Toby suffered a heart attack and a relapse of his depression, while in one of This Is Us's most heartbreaking moments, Kate experienced a miscarriage. The couple also navigated a second precarious pregnancy and Kate went into labor early, resulting in their son being born partially sighted. Throughout all of these difficult times, Kate and Toby were always there for each other and made each other stronger.

Good Idea: Their Dreams Are Taking Them Different Directions

Kate and Toby talk on a bridge in This Is Us

Kate and Toby have both been struggling with finding their purpose. After Toby was laid off, he began to feel as though he were not enough for his family. A new job opportunity arose which he couldn't turn down - even though it meant spending three days per week hours away in San Francisco.

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Kate moved from one job to another without finding her calling, whether as her brother Kevin's assistant or in multiple failed music careers. But as season 5 came to an end, Kate found a job that made her feel like she was making a difference, as a music teacher at the local school for blind children, including their son, Jack.

Mistake: They're At Their Best Together

Toby and Kate cuddle in their robes with coffee in This Is Us

There have been many couples in This Is Us that are perfect together, and Kate and Toby have shown that they deserve to be among that group. They couldn't have been more different in terms of their personalities, but their differences were what made them work so well.

Opposites do tend to attract, especially on television. Kate was often the voice of reason for Toby as he embarked on impulsive ventures, and Toby provided Kate with the support and cheerleading she needed in her most insecure moments. As individual characters, Kate and Toby have never been the series' strongest. But together, they've been a perfect match.

Good Idea: They've Fought More Than The Other Couples

Kate and Toby sit and look angry in This Is Us

All of This Is Us's couples have had their issues. Jack and Rebecca fought about her feeling unfulfilled as a housewife and mother, while Randall and Beth nearly split after he chose to pursue a political career. But Kate and Toby have argued far more frequently than the other couples, and their arguments were never easily resolved.

In many cases, it even seemed like arguments were brushed under a rug rather than being dealt with. Recent episodes in season 5 contained heavy-handed suggestions of Toby facing immense pressure and reaching a breaking point, only for him to later act as if everything was fine rather than admit to his unhappiness.

Mistake: Toby's Part Of The Family Now

This Is Us Kate Toby and Jack

The Pearson family has always been incredibly close. When Toby first entered their lives, some members of the family, including brothers Kevin and Randall, weren't all that fond of him. But over time, Toby has grown close to most members of the family, especially now that he and Kate have formed a family of their own.

Beyond the immediate Pearson family bloodline, Toby also formed a second family of his own in "the other big three," his friendship group with fellow Pearson spouses Beth and Miguel. The dissolution of Kate and Toby's marriage would inevitably change all of these social dynamics for good.

Good Idea: Toby's History Of Lying

Toby gives Kate a gift in This Is Us

After being in an abusive relationship in her youth, Kate already had many insecurities when it came to being able to trust her partner. Over time, however, Toby has routinely abused the trust she has given him, showing himself to be a habitual liar in the process. All characters in This Is Us have kept big secrets, but Toby has kept harmful secrets both big and small from his wife.

Toby has lied about his dieting, his secret exercise regimen, and communicating with coworkers about marital troubles. In more serious matters, Toby has also lied about how he feels about raising a child who is blind and accepting a job offer hours away. How could Kate trust him any longer after this pattern has emerged?

Mistake: They Were Finally Figuring Parenting Out

Kate and Toby with their son

After baby Jack was born premature, Kate and Toby both struggled with the road ahead for raising a child with complex medical needs. Once they learned Jack's diagnosis of retinopathy of prematurity, the couple did all they could to adjust their expectations and provide Jack with all the accommodations he would need.

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Kate was eager and excited to learn about all the opportunities available for blind children, and she even attended a retreat for families with blind children. Toby dealt with his feelings of insecurity and his fear and learned how to bond with Jack during his time as a stay-at-home dad. Although the two had missteps along the way, they were just getting into a real groove when it came to parenting, especially with the addition of their adopted daughter, Hailey.

Good Idea: Kate Deserves Better

Kate in the season 5 finale of This Is Us in a wedding dress

After everything Kate endured, she deserves to find her happily ever after. She lost her father at a young age, she never felt like she was good enough, and always felt uncomfortable in her own skin. She was abused in her first romantic relationship and struggled to trust anyone again after that.

Kate thought she had finally found someone who would give her the fairytale ending in Toby. But time and again, Toby has failed her, and he has often left Kate hanging in the moments where she has needed her the most. No matter how good they may have been together, Kate deserves better than the husband Toby has turned out to be.

Mistake: There's Not Enough Time Left To Make It All Make Sense

Kate and Toby facing one another talking on This is Us

It was one of the most shocking moments in This Is Us's season 5 finale when it was revealed that Kate was getting married again, and to her boss Phillip, no less. But with only one season left, fans have already begun to doubt whether the series will be able to depict both the end of Kate and Toby's marriage and the development of Kate and Phillip's relationship.

This Is Us has always managed to deftly navigate between different time periods and relationships over the course of its 5-season run. But it's a tall order for even the strongest writers to find a way to break up one couple, establish a second couple, and bring that couple all the way to marriage all in the span of one last season.

NEXT: 5 Reasons Kevin & Sophie Need To End Up Together In This Is Us (& 5 Reasons They Need To Move On)