I'm sure he's happy. And he'd want you to be happy too.
— Excerpt from her ex-husband Sam's letter
Kay Finch (née Carlyle) is the ex-wife of Sam, and the mother of Dawn, Gus and Gregory. She divorces Sam following their son Gregory's death, for which she appears to have felt personally responsible.
Kay is a middle-aged woman with light brown eyes and short, dark brown hair. During Gregory's flashback, Kay wears a pink and purple outfit with a plaid skirt along with a green pendant around her neck.
Kay appears to have had a strong fondness for the color pink, as the "only mark she left on the house" was the garishly-decorated pink bathroom connected to Sven and Edie's room. Based on Sam's note to Kay, she seems to have been consumed by guilt after Gregory drowned. In the letter, Sam reassures her that it wasn't her fault and that she did all she could; however, Gregory's death was implied to be the catalyst for their divorce.
On a desk in Sam's room, a box of Kay's belongings, a tree-shaped carving holding several necklaces, and an envelope addressed to Kay alongside an empty Sparrow Airlines plane ticket holder can be found, implying that she had flown somewhere else following her divorce. The envelope is addressed to Kay Finch, which indicates that it was ordered before the divorce was finalized.
There is no mention of Kay after she divorces Sam, so it is unclear whether or not she is still alive. Kay, along with Sam's second wife, are the only two characters within the Finch family to have their fate completely unknown. As the other spouses of Finch family members (Ingeborg, Sven, and Sanjay) all eventually meet their own deaths rather young, it it possible that Kay divorcing from Sam freed her of the curse. As the three others also failed to outlive their Finch spouses, it is possible that Sam's death kept both Kay and his second wife free of the curse.
- On the Finch's family tree visual, Kay's leaf (signifying that she married into the family) is the only one that remains attached to the tree, while Sanjay Kumar and Ingeborg Finch's leaves are both detached.
- Though muffled, Kay's arguments with Sam over the phone during Gregory's story can be overheard. During the first call, she tells him that she doesn't want him to come home and that "nothing ever changes"; during the second, she tells him she's afraid of him and that he's acting ridiculous, reassuring him that Gregory is fine and mentioning "[his] entire family". This may suggest that Sam's paranoia over the curse was a factor in their divorce. She also threatens to call the police if he shows up, indicating that their relationship had soured considerably at that point.
- Kay's divorce contract states her maiden name.