This mod will enable gay and lesbian marriages. Men can marry lords of a kingdom, and women can marry noble ladies.
To propose a lord as a man, you must talk to an unmarried lord and ask to cement an alliance with their house. They will talk about their unmarried female relatives, but you can insist that you are more interested in them.
To romance a noble lady as a woman, you must talk to a lady at a feast and declare your admiration for her.
Original thread: https://forums.taleworlds.com/index.php/topic,343671.0.html