Like so many British movies the love/hate is so subtle it's difficult to tell the difference. I too found out too late my marriage was not what it pretended to be. She had 3 people in her relationship but could never know she was 3rd. I would call this anything but a successful marriage. It is for him a settlement when love is gone. It's terrible to find out the truth and you have wasted your life as the person who was setttled for rather than loved.
He only wanted one child, the one he could never have.