I find Doctor Who interesting as a study of women. In the New Doctor series, the sidekick might already have a boyfriend (Rose with Mickey, Amy with Rory), but as soon as she sees the alpha-male Doctor it wipes the beta-male boyfriend out of her psyche. She then spends a season or two pining after the Doctor who has no romantic interest in her, and being very dissatisfied with the boyfriend, or forgetting him entirely.
I see this happening in real life as well, women ignoring the guys who might really want them, to spend time chasing after "exciting" guys. Meanwhile, the "exciting" guy finally dumps the girl and moves on to a younger/hotter/tighter model when the older girlfriend pushes him on commitment.
The dynamics may be more interesting this season, what with the Doctor being officially married to River Song, while chasing around Time and Space with Ms Hottie.