Why does the husband leave the family in The Others?

The husband is killed whilst on the front line and just comes home to say goodbye to his family before going back to haunt the place where he was killed. He regrets going to war more than he can say, but feels destined to haunt the trenches because for some reason the 'law' is that the ghosts must haunt the place where they died (like the three housekeepers who stayed there when "All the other servants left"). The husband partly realises they're all dead and understands this 'law' of having to haunt the place of death, but can't put it into words to explain to his wife.

I also think the big thing is that he can't relate to any kind of normal life anymore after the war, even though he loves them all. I think it's that he can't explain to them what he's been though or live as though it never happened, that's why he doesn't explain why he feels so driven to leave and go back to where he feels he belongs (maybe his delusion isn't that he's alive and at home like the wife, but alive and at war, just nipping back for a home visit, even though he partly understands they're all dead but is too confused to mention it) and leaves whilst his wife is asleep because he's struggling to comprehend the situation himself.

He obviously feels his 'place' is where he died, despite the extreme regret he has at going to war. I think the narrative is that in his mind he comes back to see his family after his death to say goodbye to them forever and then go and be at the trenches (where he feels he belongs, just as the wife and children feel they belong in that house).