"This is different from the stable marriage problem in that the stable roommates problem does not require that a set is broken up into male and female subsets. Any person can prefer anyone in the same set."
You know that not all gay people prefer all other gay people? If a gay man prefers a gay woman, we call them straight.
The set of gay men isn't broken up into male and female subsets, and neither is the set of gay women. You don't have this cross-set matching which seems necessary for the stable marriage problem: you indeed have a single-set stable roommates problem, or perhaps two such single-set problems, one for gay men and one for lesbians.
You know that not all gay people prefer all other gay people? If a gay man prefers a gay woman, we call them straight.