How can my same sex spouse, who is a citizen of the US, get Greek citizenship like me?

Citizens of non-EU countries that have a residence permit of Greece are entitled to apply for Greek citizenship by naturalization in the following cases: after 7 years of permanent and legal residence in Greece; after 3 years of permanent and legal residence in Greece provided that they are married/have a cohabitation agreement with a Greek citizen and have a child with him/her; after 3 years of legal and permanent residence if they have an underage child that holds Greek citizenship. Furthermore the Greek law acknowledges the cohabitation agreements between same sex partners, but not same sex marriage.