IiRC it was more so that the Church got actual fiefdoms and wanted control so that potential priestly families wouldn't just distance themselves into secular noble houses, taking lands with them.

Fiefdoms and related duties originated from kings, so the church wanted similar parallel rights over their vassal priests.

This great synod absolutely forbids a bishop, presbyter, deacon or any of the clergy to keep a woman who has been brought in to live with him, with the exception of course of his mother or sister or aunt, or of any person who is above suspicion.

This is what i was referring to, but it may have been a later council? It's canon from what I've read, but not specifically about marriage, but "keeping a woman".

https://www.papalencyclicals.net/councils/ecum01.htm