From Peace Corps Wiki
Peace Corps service can be a rewarding, enriching experience for married couples. Married couples make up about nine percent of Peace Corps Volunteers. In fact, some Peace Corps countries have couples-only programs. In all cases, both spouses must serve as Volunteers and live and work in the same community.
Just think of the stories you'll be able to tell your grandchildren someday.
Peace Corps is unable to place couples with dependent children and cannot guarantee placement in the same country of couples or friends who are not legally married. Applicants can begin the Peace Corps application process while engaged, but must be married at least 12 months before departing for their overseas assignment.
 External Links
Married Couples Official US Peace Corps Website