The Question and Answer section for The Five People You Meet in Heaven is a great resource to ask questions, find answers, and discuss the novel.
I don't recall a fight. At the end of chapter 1, the narrative cuts to the first of many birthday flashbacks. This one takes place on the actual day of Eddie's birth in 1920. Eddie's father is smoking cigarettes in the waiting room when a nurse...
I think that Eddie's gambling was tough but he eventually forsakes it. The inability to have children was another stressor. Marguerite has a brain tumour and, although she dies, they manage to stay in love until the end.
The second lesson.... from the text:
"We all have to make sacrifices. It is a part of life. It's supposed to be. It's not something to regret. It's something to aspire to; May it be little or big sacrifices."