Indeed, the largest source of litigation in the Middle Ages is family law, with cases ranging from actions for dower or adultery to claims of bigamy. While the validity of marriage is not, today, a huge burden on the courts, this was not always the case. Hemholz, in Marriage Litigation in Medieval England, probably the best book on this subject, gives some examples of numbers on page 25. There were, from November 1372 to May 1375, 98 family law cases brought to the Consistory Court at Canterbury. Of these 10 were for divorce, 10 miscellaneous, and 78 were petitions for the church and state to declare a marriage valid. The only possible sense in which it was true that the state’s permission was not required is that in most countries the ecclesiastical courts would deal with these cases rather than the royal courts, a jurisdiction that was retained in England until, if I recall correctly, 1847. The church courts dealt with a lot of secular law, however, including property law and their judgments were enforced by secular authorities, with little distinction between the two systems; arguably less, for instance, than between federal and state courts today (one of the bigger difference in both cases being that appeals could go to Rome/ DC instead of staying in state).
The statutes that the ecclesiastical courts interpreted were generally passed by royal authorities. Henry II, for instance, reformed Ireland’s marriage laws substantially in the 1160s and 1170s, requiring formal celebration of marriage, outlawing incest (both consanguineous marriage and extra-marital sex with stepmothers, the daughters of departed wives and with sisters in law), and ending the custom of marrying the brother’s widow after a substantial marriage. You may note that this meant that he outlawed marriages that were supported by family on both sides. This was greeted with joy by Pope Alexander III, as most Christian states had always prohibited incest, because defining marriage is something that both church and state were involved in.
A very, very small quote that I frequently offer those who think that gov’t only recently “got involved” in marriage.