Reva Shwayder Gothelf, 91, an artist whose marriage as an octogenarian was chronicled in an Academy Award-winning documentary. Her marriage to another artist, Louis Gothelf in 1986, when she was 84 and he was 85, became the subject of “Young at Heart.” The popular documentary, which focused on her career and how she coped with the death of her first husband after a 62-year marriage as well as with her remarriage, won an Oscar for short subjects in 1983. A native of Chicago educated at the University of Chicago, she taught herself to paint in middle age and exhibited in such venues as the Detroit Institute of Arts and Pennsylvania Academy of Arts. She sold hundreds of her works to private collectors and such corporate clients as Ford, Chrysler, IBM and Kreske. On Thursday in Franklin, Mich., after a stroke.