Shallow Grave
I watched a British film in 1994, Shallow Grave.
The director is Danny Boyle, who also directed Trainspotting.
This is about friendship, but it's not so simple.
I think friendship is very emotional relationship, therefore once the relationship gets wrong, it's just getting worse and worse.
Let's imagine that you go for a trip with a friend of yours and have serious argument. You might forgive him or her if they were not your friend, but sometimes you couldn't do it because they ARE friends.
This film shows the complexity of friendship very clearly. You might feel uncomfortable seeing this film, but it is interesting anyway.