This line from the Washington Blade says it all:
"We are tired of being seen as the embarrassment to the [Democratic] party." (Kevin Cathcart, Lambda Legal)
In contrast, the Libertarian Party doesn't see the LGBT community as an embarrassment. In fact, Libertarians have supported equal rights for same-sex couples to form a contract, which includes marriage, ever since our first platform in 1972.
Unfortunately, with puppets of the Democratic Party entrenched in the leadership of the largest LGBT advocacy groups, most people have never heard about this. If queer Americans knew how often their rights are traded for an extra 1% in spending on some Democrat's pet project, there would be Stonewall-like riots outside the Democratic Party conventions.