I'll bite; why is a love interest not an actual character?
It's not an actual character if it's the ONLY character that women get to play.
If you apply both the Bechdel test and the "gender reversed Bechdel test" to movies, you will see that this is more than a curiosity. The results are overwhelming. If you're a male actor, you get to play someone who has conversations with other male characters about lots of topics. If you're a female actor, you get to play the love interest, whose only conversations with other women is about men. The result is that women are portrayed as being only there for (the pleasure of) men.
The results will vary depending on which films you count. Independent films are perhaps (but not necessarily) better than mainstream blockbusters, but far fewer people see them, so they have a much lower impact anyway.