Many countries still do not allow same sex marriage and have problems with giving same rights for homosexual people not because they want to prohibit the love  between two homosexual people but for the stabilization and perpetuation of society purposes.  Stabilization and perpetuation of society  because we all know that homosexual partners do not have the capability to create children meaning, same sex marriage changes the purpose of the civil institution of marriage. Unlike natural marriage, it has the capability on bringing up next generation on raising children to become good citizens.  Same sex marriage merely validates sex partners. Even some homo partners adopt children, still, the truth is there--they are not the biological parents of those children.  Religious beliefs and cultural orientations regarding homosexuality are also big factor. The Bible teaches us that man is created for woman and vice versa.