Just got married, here's how it went down
I joined the Dark Brotherhood, and after doing the second quest I had to kill 2 people for this one girl who called on the Dark Brotherhood to kill them.
I dispatched both and as a reward, she gave me gold and said she had affection for me and gave me her ring. She started walking away so I talked to her again and told her I love her and we got married a day later.
She now lives in my house at Whiterun :D
Name's Muirl