In my opinion, the relationship between Serana and the dragonborn is probably the most in depth relationship throughout the entire elder scrolls series.. To not have an option for marriage, if you want that sort of thing, is quite insulting. Now saying you could marry her, it would be so out of character to have the wedding in the temple of Mara, so instead have the wedding at the castle and make it a bit darker.
Just my opinion...
This. While personally I wouldn't marry her (i think). Mainly because I never see my in-game wife as it is. RP'ing, the wife stays home and makes me money. A follower OTOH, i see all the time. And she is essential to boot.
But they did go and create an actual "relationship" - such as it is - that no other npc in the game can come close to. Even after the main quest, upon entering Kagren-whatever, she comments that she is glad I am with her to see it.... Bethesda really are making us fools for love.
She is just the best in the game. But I like her as a follower, and I can take that. A marriage option might be nice, but
only if it really adds more depth to the already solid relationship the PC and Serana already possess. svcks for me if they do - I am already married.