A while ago, I finished watching Revolutionary Girl Utena. Throughout the show there were implications, at least I thought there were, that the two main characters, Utena and Himemiya, were more than just friends. I asked my friends what they thought about this and they just stared at me blankly for a while. They said I was crazy to think that they were lesbians and that would ruin the “beautiful relationship” they had. How does that ruin anything? Would their response have been different had one of them been male?
I hear this protest a lot… I strongly disagree with it, and once wrote an essay on the things I considered wrong with that idea, but I’m not sure where that is right now. My main problem is this strange idea that Utena and Anthy can’t be friends anymore if their relationship becomes sexual, which strikes me as terribly wrong-headed. Sure, if Anthy lured Utena into the Akio Car and cheesy music played, it’d be wrong. But if they’re in love, love is about as beautiful as you can get, platonic or no. I think one of the major themes in the show is about the difference between contrived love (prince and princess) or agonizing obsessive one-sided love (Juri and Shiori, Miki and Kaoru) and love between two people who truly come to know and care for each other, including their faults.
Since they make out while nude in the movie, I somehow think the director did intend them to have a non-platonic relationship. 
It can. I have no idea about the movie that you’re talking about, but often movies/books/tvshows/whatever will explore the relationship between two characters and we will find out that they are attracted to each other, they’ll get it on and away we go.
This often does cheapen the relationship, especially if it is poorly written, because having the characters fall in love is the easy way out. Love can really be a very cliched emotion, and it’s been explored in countless ways throughout history. Often an interesting, intense, but platonic relationship is cheapened by having the characters reveal romantic affections for each other. It’s the writer taking the easy way out, taking a well explored path for her characters, rather than exploring what could have been a more interesting relationship.
I guess I’ll have to chime in on the “sometimes” vote myself.
Probably, the best - or at least best known - platonic relationship was Mulder and Scully in the X-Files. They cared deeply for each other, and half the time they were either flirting or bickering like an old married couple, but there was never an overt romatic element to their relationship and that was okay. They were just friends, very good friends. Friends with that undertone of sexual tension that, at least on tv and in the movies, always seems to exist when a man and a woman who are both heterosexual have a friendship, but still friends.
Then they had to screw that up by getting them together, but since the show totally sucked by that point (The X-Files didn’t last nine seasons, it ended after season five, season five I tells ya!) and I’d stopped watching it long before, I suppose it hardly matters.
So in conclusion, it ruined the Mulder Scully relationship, but because of how it was done, not because it was done.
It does seem that for whatever reason, tv series that rely on the sexual tension between its lead characters tend to dip in quality (and definitely dip in viewership) when the romantic leads actually get together.
Moonlighting is probably the most notorious example, but it also happened to Northern Exposure.
I’m not really sure if this is proper message board etiquette, but thanks to the people that replied!