Church and Marriage in the Middle Ages

A while back, someone claimed that the medieval Church really didn't care much about the rules of marriage one way or the other, since marriage was a matter for this world and the Church was concerned with the next world. I got involved in a little argument over this, inasmuch as (if I recall correctly) the argument being advanced was that the prohibition against homosexual marriage was at best a late medieval invention.

I may remember the argument wrong, and I regret the error if so, but it has stuck in my head a long while., because it came to mind immediately today while reading Humphrey's latest entry at James Hannam's Quodlibeta. Humphrey is writing a series of articles on the family in the Middle Ages, and whaddaya know, even the early medieval Church was deeply interested in the rules surrounding marriage.