Marriage Rites, Customs, and Ceremonies, of All Nations of the Universe (1822)
This snippet gives some insights into annulments, divorce, and the legal implications of marriage for women.
Here are some links to other resources about marriage in the Regency era:
http://www.jasna.org/publications/persuasions-online/vol36no1/bailey/
Regency Culture and Society: A Scathing Letter on the Marriage of Minors