She started when she was young, around 18-20 (still deciding) and at age 23-25 she went to the Companions for a few months for a little 'adventure', contracted lycanthropy willingly, then after that stayed 2 years at the College before spending her wealth that she gained from enchanting, hunting, and many other things, on buying a house in Windhelm and Solitude.
I remember there was confusing regarding the story of Marie the maid and the two houses. Dabiene was chased by the Chosen from Solitude where Marie stayed. She mentions that the Windhelm property was taken from her by none other than Ulfric himself. She also assumes that her Solitude property was takin after she left along with Marie. So she probably either was taken off to Windhelm as a hostage in the dungeons, or in Solitude being in a VERY, horrible situation.
Where ever Ulfric is staying at though, she thinks Marie is going to be there just to get back at Dabiene for turning him down so many times.
As for that theory Operator, it might work, but what if those characters come back somehow? We could say they were abducted by the Falmer, because there is this little misc. adventure where the falmer do kidnap travelers and merchants. You find evidence of this in a cave near Dragonbridge in the Reach.
I was also thinking Simus, that Dabiene could possibly hear something downstairs, gets up, finds one of Ulfrics assailants looking for her. She kills him, finds a note to Maries location and yea. Alice might freak out that there is a damn assassin in the house and Dabs tries to comfort her.
OR, there would be a knock at the door and when she opens it a note lies on the stone steps. reading it she finds out about Marie.
I was going to put the scene in the Marketplace for extra drama but I just wanted to see what you think. I could do this scene later but it's up to you lol.