Ebbie I fear you have "lost the plot."

The legality of "marriage" whether homosexual or heterosexual, is no guide to the promiscuity of the "marriage" partners.
I know people who live together, unmarried, and are completely monogamous, I also know of others who have been married for many years yet attend "swingers" parties.

The danger appears to be male to male penetrative sex, whether done in a monogamous relationship or a promiscuous one.
I have always suspected that homosexual "marriage" was a device to attempt to normalise the practice in much the same way as the word "gay" has been used to deflect public disgust with the homosexual act.

I have absolutely no belief that a piece of paper granting marriage "rights" to homosexuals will cause them to become,as a group, less promiscuous.
From the statistics, promiscuity goes with the lifestyle

Let us begin to be honest, The homosexual lifestyle is dangerous, as dangerous as drug or alcohol abuse and very much more dangerous than other unusual sexual behaviour such as incest....so why not scream for the rights of incestuous couples or drug addicts?