This again. This can be done without mods and by using the console. In the console mode, click on the NPC you wish to marry (make sure it is really her/him who is clicked, and not something in the foreground or a piece of the ground ~ stay close to ensure), and then type in these commands ('Enter' after each one): setrelationshiprank player 4 addfac 19809 1 addfac 5a1a4 1 ..But I heard there are multiple problems with the Serana character, because she lacks the sound files for marriage dialogues (which will never be solved by mods), and spouse behaviour files (which could be added easily).
