Hello – I don’t have many memories of this film but it’s been bugging me for years.

There is some type of war/apocalypse that breaks out. There is a man and wife who live in a house with lots of land. A male intruder attacks them and holds them hostage as he’s trying to flee the war/apocalypse. The intruder and wife eventually start having an affair although the wife is mostly forced into it to stay alive. She is allowed to live in the house but the husband is made to live outside. She then sleeps with her husband once in secret by the side of the house, but also sleeps with the intruder. She falls pregnant but doesn’t know who the father is. One of the last scenes is the three of them standing at the front of the house ready to fight as they hear people coming to take their land.