I saw in a marriage thread someone said they did this with console. I just tried that on her with addtofaction 5c84d 2, but it didn't work. I have already done the quest for her aunt.

From what I've seen, it seems to take certain numbers after the base ID depending on the follower/faction you're adding them to. There's likely a reason behind it that actually makes sense in the grand scheme of things, but I'd try changing the number at the end to anywhere between 0 and 4. And make sure you got her targeted, I kept trying to make Cynric marriage-worthy one time and realized after a couple minutes that I was trying to get the wall behind him to marry me.

Yeah, I got her targeted and I am using 2 as the faction value, which is what worked on Senna. Still not having any luck with Vivienne. I was planning on buffing her health and magicka and giving her some conjuration spells like I do with Senna sometimes....

I'm fairly certain it depends on the NPC. Before 1.5 dropped, the faction value for Lydia was 1, for example.

Or just target the old girl, and type setrelationshiprank player 4 into the console. Forgot that's a thing but yeah, since she's not usually marriage-worthy in the game without the console, chances are her highest default is 3 (ally) as opposed to 4 (lover.)