It was very simple really. They were both alone, haunted by their own tragical lives.
So in a way, it only made sense they seeked comfort in each other. Both being there for each other when reality got too harsh.
She - a woman who wanted her mother`s approval so bad that she would do anything to get it. And he - a man haunted by his past and whisful thinkings of what could have been.
They both knew it wasn`t true love, that it would not last - not for long at least. But they accepted it, using each other in a rather selfish way. He used her in order to forget about Lucy and Jacinda, to forget the way his family always seemed to slip away from him. And she used him because he understood. He never pushed her to talk if she didn`t want to. But at the same time he was always there, ready to listen when she was ready to talk.
And in a way it was perfect.
After all it was their little getaway from reality.