At this point, most fans are taking it for granted that Kate and Toby are getting divorced on This Is Us. All the signs point to a divorce, from Toby's absence in the flashforward to Season 5 to his complete unfamiliarity with Kevin's house in the scenes from 2034 that aired at the end of Season 3. That means, of course, fans are hoping to see Kate find a little happiness, and maybe, for the first time, a man who isn't so self-centered... The latest question is, will Kate and Gregory end up together? It's a possibility, but probably not one that would happen overnight.
Gregory is Kate's next-door neighbor, the one who she meets under less-than-ideal circumstances when he grumpily yells about how Toby is parking the minivan. But they quickly both realize they've misjudged each other. She realizes he's working through the after-effects of a stroke, and his "grumpy persona" is just how he talks now. (Moreover, the minivan is a problem for him.) He realizes she's not some thoughtless stay-at-home mom who's self-centered about her family, but someone with a visually-impaired child and a crumbling marriage.
Their unlikely friendship started with slow walks around the block together. But it's become more than that. It might have seemed like a fluke that Gregory was the one who was around when Jack ate his first solid food instead of Toby. But in reality, it's a reflection of who is in Kate's life and who isn't.
By the time fans realized it's Gregory who Kate called to tell all about the retreat, and not Toby, it has become apparent their friendship has evolved into far more than walks. She might not be in an emotional affair the way Toby was verging with Lady Kryptonite. But Toby isn't her best friend anymore. Gregory is.
Does that mean Kate and Gregory will fall in love? Not so fast. These are two people who have been through a lot mentally and emotionally and who probably don't view themselves as potential partners for anyone, let alone each other.
If Gregory and Kate wind up together, it will probably be a slow and steady build over many episodes. And it definitely won't be anytime soon.