Lesson 1: They might be too willing to change.

Sitcom characters: Ann Perkins of Parks and Recreation, Penny Hartz of Happy Endings, Hannah Horvath of Girls, Jane Forrest of The New Normal

There's a number of single women on TV who are just a tad too willing to adjust their lifestyles to the expectations of the men they date. 

Take these women, for instance:

• Ann on Parks and Rec is actually known in her circle as the woman who takes on the hobbies of her boyfriends, such as Chris' health obsession.
• On Happy Endings, Penny spends an entire episode making up dates that involve helmets just so she doesn't have to tell the guy whom she's dating that she had a concussion and has to wear a protective helmet all the time.
• Hannah on Girls does all the kinky stuff that Adam wants her to do, even when she finds it awkward or unappealing.
• Even the grandmother, Jane Forrest, on The New Normal changes her entire look because she has the hots for a younger man.

Watch your step when it seems like the woman you're dating shares every single one of your interests. You might end up sleeping with a female clone. Though, who knows, maybe you're into that.