Why did Iris + Roy split up?

I don't think they had a specific "conscience uncoupling". Roy was a natural, a "can't miss" prospect whose plan was to get signed to a baseball contract and send for Iris when he accomplished that. After he met the milf/ho on the train, went to her hotel room, got ventilated, and spent a year in the hospital, he was too ashamed and embarrassed to go home and face her. What would he say to her? How would he explain his derailed baseball career?

Remember the scene at the candy shop when Iris asked Roy what ever happened to him? His answer was that "my life didn't turn out the way I planned"

It is bad to drink Jobu's rum. Very bad.

I don't think they did.

In the film's story the implication seems to be that he strayed in terms of being sexually faithful to Glenn Close's character, and then felt ashamed for the act, and only when he got enough courage to face the stigma did he come back and face the music, so to speak, and win the heart of the woman he loved.

In the book Roy loses interest in Iris when he finds out she's a grandmother. He finds it unattractive.

Have you seen Iris? Lmao vomit!!