Who really cares, let them marry if they want it wont change my day.
It's only bullshit religious groups that's stopping them because some imaginary god has told them it's wrong.
of course it is not because of a religion or a particular group like your opinion mentioned above, do not blame a thing because religion, God teaches people through religious teachings in order to better life, besides there is no religion that teaches that people marry fellow the kind, humans are created by God with different sex so they can marry and produce children as their offspring.
I personally disagree with the existence of same marriage, in addition to contrary to the teachings of God it will cause a great negative impact on human development itself.