I do like open ended ending but not always. This is one of those that I like. And when I first saw it, my interpretation was that he actually went along with it. May be because that's what I
wanted him to do? And I think it might even be a more cruel ending? However, I was also pissed off because I wanted to know what the director intended.
On top of that, I was toying with the idea that she was not actually blinded and just pretending. It's just the way she looks at the waiter in the last scene i think.
Anyway, later I was reading into some articles online about the ending. One of those articles mentions, that if you sit through the credits, you'll hear the music that plays after the initial song is "ambient" like music. And it was suggested that it sounded very much like waves hitting a shore ( and it actually does sound alike after listening). Hinting that he was in fact turned into a lobster. Dont know if it's true or not but it would be cool for the director to sneak that in if that was his preferred ending.
