During the later medieval period (10th to 15th centuries), a new scholastic way of thinking allowed the Church to solidify doctrine, leading to the formation of ecclesiastical law.
[2][3] Biblical references to marriage, like that found in 1 Corinthians 7 alludes to it as a preventative measure for "sexual immorality."
His 12th century work, Decretum Gratiani, became an early text example for other canon law studies and it is here where the earliest account for marital debt is found.
Gratian is also quick to point out four main reasons people may have for getting married: that is for offspring, to pay the debt, or the obligation of sex, for incontinence, or to satisfy lust and for the sake of pleasure.
[4] One notable example of the strength of this bond, was when a husband wished to leave his marriage for a monastic life but he remains in a sexual debt to his wife.
If a man wanted to go on crusade he needed permission from his wife, because "his departure would deprive her of the sexual solace that he owed to her.