I totally concur with what you say. Jeremy never HAD to work his socks off at school. Sheila -leaving aside her illness- didn't HAVE to find a successful career or marry a wealthy man.
Exactly. It sounds like Jeremy made some kind of attempt to do other things jobwise, but in the end he toed the line and went into farming. Sheila was said to be a model, but I doubt she would have made much money out of that. She was a very pretty girl, but top model? I'm not sure about that. Her husband appears to have been unemployed at least at one stage, so who could she turn to other than her parents?
If both of them had decided as soon as they became adults that they would stand on their own two feet and pay their own way, even if that meant being a bit broke, the family problems probably wouldn't have happened.