Health Insurance: Same Sex vs Opposite Sex Domestic Partner Issue when Applying for Health Insurance

My question involves insurance law for the state of: OHIO

Is there any case law, particularly from Ohio, regarding eligibility when applying for health insurance for treating opposite sex domestic partners the same as same sex domestic partners. Is this a matter of having the same residency?

It appears to me that insurance companies are giving priority in terms of acceptance to same sex over opposite sex domestic partners.

Health Insurance: Same Sex vs Opposite Sex Domestic Partner Issue when Applying for Health Insurance