Ancestry is very informative, if correct. According to a tree she remarried in Florida in 1973 and died in Lake City, Florida in 2006 as Mary Ann O'Neil. The tree is supported by an entry from the US Social Security and Claims Index which gives her birthdate of 15/5/1946, her birthplace as Brockton, Mass. and her various surnames as MacLeod, Waite and O'Neil. She married Leslie Edward O'Neil, who divorced his first wife in Florida in 1971 - so perhaps this all hangs together. The school picture of her on the tree at least matches hair colour (see attached).
Back in 2008 the owner of the tree posted the following;
" This is a very difficult story to tell. While living in Brockton, Mary Ann left her husband and young children and disappeared. SHe was found in Ithica, New York and brought back home. A few months later, she left again and was not heard from again. We do not know if she is alive. After seven years her husband went to court and shortly after re-married."
I assume they found the Social Security entry subsequently and updated the tree.
I cannot confirm all of this and am always reluctant to rely on family trees, but in this case the owner seems to have details of events around 1971, and official records back the tree. On balance I am inclined to think this case is as recorded, but further proof is needed.