Oh I feel your pain..
Ive been with someone like this for 4+ years...

There has to be deeper issues here. Its such an uncomfortable way to live your life around somebody else's moods.
Do you know anything about his childhood?
Does he just prefer total freedom and call upon you when he needs you?

Ive just come to a cross road with my partner who behaves in this same manner on many different levels.
He is currently seeing a psychologist to help him be good for himself and to me.
Its going to be a long journey but im hoping worth it in the end.

You should not be shot down for showing concern.
If this continues either he seeks help or you get away and find someone thats on your level and understanding.

All the best.