Metaphorical 'vampire' girlfriend

I think this movie was excellent when considered from the metaphor standpoint. Danika was the stereotypical girl with baggage. She's crazy-hot, but she's also just crazy. Every time you see her, she's in a different mood, for no apparent reason. She goes from crying uncontrollably to out-of-control horny in a split second. All of your friends notice that she's "sucking the life out of you", and eventually you'll have to choose either her or your friends - it can't be both.

I definitely think this analogy was intended by the filmmakers, as Roger was there to spell it out for the audience as every opportunity. Did anyone else notice this, or agree?