Surprised to see everyone dog piling on Ted in other comments. Marriages at that time weren’t often based on strong footing and we’ll never know exactly how they felt when they married or how their feelings changed throughout life.

[Based only off of the summary] It’s easy to see Helen as a saint but it could just as easily be an unhealthy codependence. Chronic illness/pain/disability can completely erode a relationship over time. She pours more and more of herself into him without realizing (or denying) that there are aspects of a relationship that she can’t give. Doesn’t even have to be sexual, could be something as simple as a walk in the park or sharing a favorite meal outside her diet.