The Obssession with Homosexuality

[Fragony]

Ok then:

1) Couple A consists of two people of the opposite sex; couple B consists of two people of the same sex.
2) Couple A is allowed to marry
3) Couple B is not allowed to marry.
4) Couple A and B are treated differently aka there is unequal treatment.

To those opposed to gay marriage: what is your justification for this unequal treatment?

I am neutral on the subject, I am not against it, and I am not for it, all fine with me what's it to me. But I don't understand why they want it.