[jacalata]

He says near the beginning that they were planning to move and the house was already on the market - both of them had to leave the house. It is not always true that the husband has to leave the house.

  1. sometimes only one partner could afford the house on their own. It 
  makes sense for them to be the one that stays.
  2. if there are children, then where possible it can make life easier on 
  them if the parent who gets custody stays in the house 
  so the children don't have to move. This is more frequently the mother.
  3. if the divorce is seen as one person's "fault" then they are expected 
  to take on most of the inconvenience, which includes moving out.
  4. depending on your state and any pre-nuptial agreements and niche 
  circumstances like living in a house owned by the parents of one person, 
  sometimes the house straight up belongs to one member of the couple and
  they get to stay there.

/edit formatting wtf?

[_debug_]

Thanks! I guess what applies to the situation in the movie is point 2, about the children.