I think it all has to do with whomever spends the most time with the dogs!!! And has the food. I am the big treat giver... and Cora tends to "hang" with me when I'm home.
When we got Sadie, we were told that she didn't like men. That is probably because she had more than likely been abused by a man. However, she bonded with Russell. Due to her physical problems, he was able to deal with her more than I. He was also stricter with her. I think she liked that. She loved being with him. The would talk to each other all the time. If you guys remember the wookie from the first Star Trek movie, well... they talked to each other, both sounding like a wookie!!!
Kira is happiest when we are both in the same room together. She will play contentedly with one of her toys. However, if I'm in the bedroom and Russell is in the den, then she is restless. She's just very needy, and wants her "people" with her, together, all the time.