Ritual in every home he breaks into
1) he fixes something that's broken
2) he fixes something to eat
3) takes a picture of himself next to another picture
4) does the laundry??
maybe the simple explaination is that he does this because he wants to own this other life he doesn't have for himself. wanting the tranquil family life he imagines in them but.. something is still missing. just saw the movie so it's not fully formed in my mind yet but maybe some of ya'll can throw in a few interpretations.