Spouses die, spouses leave, and people get divorced. The details of your ancestor’s marital status can aggravate your research, particularly in those times and places where a woman takes her husband’s name.
I’ve been searching for a passenger list for a female ancestor whose first husband died in Germany in the 1840s. By 1870 she is in the United States with a different last name. But there is always the possibility that there was a husband after the one who died in the 1840s and before the one she was married to in 1870.
And that would be her last name on the manifest.