No matter how hidden, polio is the third entity in the marriage. The non-disabled partner must be able to identify with disability. The effects of polio cannot be integrated into a marriage if the experience of polio is not integrated in the polio survivor. It's not just the physical effects of polio that adds extra stress on a marriage. It's how the partners deal with the emotional and mental effects.
Disability tends to exaggerate all the ordinary issues of marriage.
The partner with polio will most likely be an over-achiever. For a healthy marriage, the non-disabled partner must have a degree of unselfishness and the disabled partner must have a degree of ego strength. Too much change, too quickly makes the relationship unstable.