BTW a bit offtopic here, but does it seem like some Co-op missions and some multiplayer maps have nothing to do with the story? I always thought that they were one in the same but I think i just realized that I guess certain missions were just made up.

I have the collectors guide and it says they were married in between but drake left her to go on more journeys because he has problems with becoming too close to someone.

Coop missions are a spin off and, story wise, should not be taken seriously. Thats at least pretty much what Amy Hennig said

Marlow died off too easily. She never seems that much of a villain.