In a marriage is the husband legally responsible to have health insurance for his wife?
A husband is not legally responsible to have health insurance for his wife. Many employees opt not to have health insurance for themselves. Health insurance is a voluntary election and no law exists making it otherwise.
However, do be aware that any medical-related debts incurred by one spouse are considered "common" debts, and as such, the other spouse is legally required to pay for them. In the event of a divorce, said debts would be even divided between the spouses, even if only one spouse incurred them.