Sologamy

Sologamy is marriage by a person to themselves. Supporters of the practice argue that it affirms one's own value and leads to a happier life.
An alternative term is self-marriage, but this may also refer to a self-uniting marriage, which is a marriage without an officiant.
Ceremonies.
Ceremonies in a self-marriage may take almost exactly the same form as that of a traditional marriage, which includes guests, a cake, and a reception. Some self-marrying programs include giving guidance, practice, and support prior to the marriage.
Self-marriage has become increasingly popular in the 21st century, especially among affluent women. , a travel agency in Kyoto is offering self-marriage packages for women, with some customers being wives who were dissatisfied with their original wedding. Some media outlets also reported the self-marriage of a British photographer in 2014 and an Italian fitness trainer in 2017.
In fiction.
Several television series have featured characters who married themselves. Those include Sue Sylvester in "Glee", Carrie Bradshaw in "Sex and The City", Holly Franklin in season 4 of "The Exes", a middle-aged man in "Jam", The Red Guy in the episode "Comet!" of "Cow and Chicken" and Rona Jefferson in "Doctors".
In the movie "Zoolander 2", the transgender model All (portrayed by Benedict Cumberbatch) is married to herself, as it's told that "monomarriage is finally legal in Italy".
"La boda de Rosa", Icíar Bollaín.