Here are the pieces.
Yet there’s still plenty show left…
Subsequently, Cassidy approaches Kevin, looking fantastic in a black dress with white trim.

Randall (Sterling K. Brown) and Kevin (Justin Hartley) share a fireside chat.Ron Batzdorff/NBC
They banter, then she heads off, and Kevin resumes his restlessness.
Randall (Sterling K. Brown) calls out the reason: Kevin’s anxious for Sophie’s arrival.
Randall reminds him she’s married.
Their ride: the antique convertible Kevin rented for Kate and Phillip.
Kevin removes the “just married” sign, so it’s not “awkward.”
Sophie reveals that she’s working as a travel nurse.
Flabbergasted, Kevin struggles to respond.
Presumably he’s delighted, but doesn’t want to be disrespectful.
While they stroll through the vineyard, Sophie hints at circumstances around the divorce but never outright explains anything.
At most, Sophie implies that she just didn’t truly love him.
Sophie eventually asks if Kevin’s dating.
He says he’s stuck in a bad pattern but can’t explain what the problem is.
Sophie thinks she understands.
Sophie takes his key card and lets herself in before him, and at last they kiss.
Things get hot and heavy.
The bra comes off the clue Beth and Madison found.
But when Kevin tells Sophie her hair smells the same as ever, she abruptly stops.
She emotionally says she has carried Kevin with her for too long and does not want to go backward.
She hurries out of the room, andTeam Sophie nosedives.
The words seemingly reference the anxiety Kevin displayed all day waiting for Sophie’s arrival.
Arielle wrote them on the napkin Beth and Madison found.Another clue solved.
Kevin soon leaves Arielle and heads to his room.
Cue Cassidy arriving at Kevin’s door, seeking help with unzipping her dress.
When she re-emerges, Kevin says Nicky thinks they should be together.
First, Rebecca (Mandy Moore) recognizes that Sophie seems sad, and it’s about Kevin.
Meanwhile, Kevin tells Randall about Sophie.
So Kevin approaches Sophie.
But before he can launch into a speech, she insists on speaking.
I’ll still mourn Cassidy, but my heart melted over this reunion.
After debating his response, Kevin pulls something from his wallet.
As a flashback reveals, it’s a valentine he wrote that day in grade school.
After he wrote ones for the other girls, the teacher introduced Sophie as a new student.
Kevin immediately wrote one for her.
In the present, as Kevin shows her the note, saying he’s always carried her with him.
With that, the two kiss and everyone in the room cheers.
Thus the puzzle is complete: Kevin’s future is with his day-one love.
It was always Sophie.
That covers nearly all possible non-app-based love-story tropes.
Now maybe all of us can have a Pearson love story we personally identify with.