Why Lady Stonehart never appeared on Game of Thrones

Entertainment Weekly

David Benioff and D.B. Weiss told James Hibberd for his new Game of Thrones oral history book Fire Cannot Kill a Dragon that the Lady Stonehart storyline never materialized on the show because they didn't want to ruin the Jon Snow resurrection. They also didn't want to diminish the Red Wedding by bringing Michelle Fairley back.