I just don't understand

From Huffington Post

House Speaker John Boehner (R-Ohio) announced on Friday that he was spearheading a process that will, ultimately, witness the House of Representatives taking over the legal responsibilities of arguing for the constitutionality of the Defense of Marriage Act.
The announcement comes less than two weeks after the Obama administration's Department of Justice removed itself from the case, declaring that it had determined the law -- which dictates that the federal government can only recognize a state-sanctioned marriage between a man and a woman -- to be unconstitutional.

I can't understand why this man and those who agree with him are so afraid.  What harm will come to them if gay and lesbian couples are allowed to marry?  What harm?  His actions actively HURT and DISCRIMINATE AGAINST other human beings, while other people's marriage affects him NOT A WHIT.  I just don't understand.  Why is he not outlawing divorce?  Heterosexuals getting a divorce hurts him just the same as gays and lesbians getting married - if that's his argument.  There are plenty more heterosexuals getting a divorce than gays and lesbians getting married; the negative impact on his view of the sanctity of marriage is more harmed by heterosexual divorce. 
It really just seems like a hateful attitude to have.  It's sad and disappointing.
With all the troubles we're having in this country he would rather spend time hurting people.  Shameful.