The entire article is based on the absurd premise that complementarity is discriminatory. The requirement that the partners be of opposite polarities does not discriminate against women because it does not say that women cannot get married. It does not discriminate against men because it does not say that men cannot get married. It does not discriminate against homosexuals be cause it does not say that homosexuals cannot get married. 

 There are some obvious reasons why traditional marriage, whether customary or codified by law, has been conceived like this; it is based on biological complementarity. 

 There are many examples of complementarity. You need to insert a key to open a lock. You cannot unlock it with another lock. 

 The article promotes a political agenda motivated by ideology.