I feel like I always end up with Lydia. She's been with me since I first became Thane of Whiterun early in the game most playthroughs, and I'm sure we inevitably get close when I have my character sleep at night. She's video-game attractive and a good fighter, what's not to like? Although one playthrough, I got really fed up with her bullcrap. I don't even know what she was doing, but suddenly her armor was gone. In a fit of rage, I led her deep into the forest and slaughtered her. Subsequently dragging her body into the nearest river, I returned home, wondering how I'd tell Sofie that her mother was never coming home...ugh.
How about you folks? Do you have a usual group of Skyrim NPC's you marry?
My top three are Lydia, Aela, and Muirui.