Jack Pearson's (Milo Ventimiglia) mother Marilyn Pearson (Laura Niemi) died on the fourth episode of season six titled "Don't Let Me Keep You," which aired in January 2022.
Jack was a devoted son who helped his mother get away from his abusive father. But when he moved to Pennsylvania from Ohio and eventually started a family, he drifted away from her.
He refused to let his wife Rebecca (Mandy Moore) travel to Ohio with their young triplets to support him for the funeral. But they showed up anyway.
Jack noticed his family in the middle of the eulogy for his mom, during which he talked about how as a child, he and his mom had escaped from his abusive home.
He thanked Marilyn's friends for creating a family for her. It's absolutely gut-wrenching to consider that he had to basically abandon her in order to be a better husband and father than his dad was.
Jack's mother triggered painful memories for him, but just because he couldn't include her in his life as much as he should have, doesn't mean he didn't love her. He only learned who his mother had become when it was too late.