In 99.44% of all human societies throughout history, marriages involve, and have always involved, exactly one male. Usually they involved exactly one female too, though some societies allowed for more than one. The notion that a marriage contains exactly one male has transcended all boundaries of time, race, geography, religion, and culture. If marriages involving zero males, or marriages involving two males (especially with no females!) could contribute to societal stability, such marriages would exist in some enduring societies somewhere. They don't.
When a practice is shared by 99.44% of all human societies, there's almost always a good reason for it. Any claim that such a practice isn't necessary should be met with extreme skepticism.
The proponents of same sex marriage have not offered any positive argument for redefining an institution that has served mankind well for thousands of years. When it comes to a change in the status quo, the burden of proof is upon those who seek a change in it.
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus