Betsy James Wyeth, the indomitable widow, collaborator and muse of the painter Andrew Wyeth, died on April 21 at her home in Chadds Ford, Pa. She was 98.

She had been in declining health for years, her son Jamie Wyeth said in confirming the death.

The couple met in 1939 in Cushing, Maine, when she was 17 and he was 22. As the oft-told story goes, Ms. Wyeth’s father invited the handsome young painter to meet his three daughters.

He was taken with Betsy, the youngest, and she with him, and she tested her new beau by inviting him to meet the Olsons, a brother and sister who lived in a squalid but atmospheric farmhouse.

Christina Olson was paralyzed from the waist down, and it was Ms. Wyeth’s intention to see if Mr. Wyeth would be shocked by the Olsons’ grim existence. As he said afterward, he was too focused on his future wife to pay much attention.