You mean like the disease free and monogamous couple that tortured raped and murdered Jesse Dirkhising? There is no such thing as a monogamous 'homosexual' couple. It is as much a figment of your imagination as the easter bunny.
That's a pretty black and white assertion. All it would take to put the lie to it is to find a single homosexual couple anyhwere in the world who are monogamous. No matter what you think of homosexuals, I think that shouldn't be a terribly difficult task.
So what you say is untrue.