First let me say I thought Jennifer Lawrence was amazing. But what was all the tearing up the house all about? I can see having a party but why destroy the home? Just did not make sense to me. Or did I just not get it?
I see it as a take on the biblical creation story (and onward)
-notice how the title of the movie, and every character's name is lower-cased except for Javier Bardem's Him. He's basically God in this story
-man arrives has a wound near his rib; subsequently a woman arrives (adam, adam's rib, eve)
-man and woman mess with the forbidden object (forbidden fruit)
-their firstborn kills the younger (cain and abel)
Skipping forward into the movie, the celebration and consumption of her child is analog to the Eucharist, for instance.
Yes. I didn't like that the destruction went for so long. From a sort of a nice living (with a few issues) it went all of a sudden really crazy and very intense and for very long time (I was thinking probably the same as the JL's character "when will the terror end?") and ended up with total destruction/death. I don't think that it's so bad with humans and Earth.