Why is OK for a single person (straight or gay) to adopt in the state of VA, but it is not OK for an unmarried couple to adopt (straight or gay)?

There is an unmarried straight couple in my neighborhood who have been together 15 years and wanted to foster a child, but couldn't because of VA' s current laws.  A valuable resource wasted; another child to age out of the system thanks to VA's antequated policies.

I support Equality Virginia's position on this:

1. The best interests of the child should be the sole factor in deciding whether a child should be placed with a prospective foster care or adoptive parent or parents
2. State-licensed child placing agencies should not be allowed to discriminate against children or prospective parents based on race, national origin, ethnicity, gender, age, religion, political beliefs, sexual orientation, disability and family status
3. The State Board of Social Services should restore to the final rules the protections against such discrimination included in the proposed rules.