It's been around as long as the BBA, but SGR[Flirt]s were only introduced with Makeb.
Edit: Presently, the BBA [Flirt] with the male twi'lek is the only male-male SGR option I know of, outside of the storyline with Lord Cytharat on Makeb. There are significantly more female-female SGR options, available to both factions, in the BBA, on Makeb, in the ROTHC expansion, with the Czerka daily-area story quest and, I've been reliably informed, in the up-coming Korriban/Tython flashpoints.
Cause if it's male-male it's a horrid thing that should be shunned by the masses, and protested against for being unnatural, immoral, unclean, and all things against Western ideals and culture. HOWEVER, if it's female-female it's perfectly reasonable, moral, clean, acceptable, and beautiful to behold, right? Right???
Hypocrisy never ceases to amaze me. Not to mention the fact that yaoi is so popular, even more so than yuri is, in both Japan and the US OF A (Yaoi & Yuri Lovers group is already on folder 4 for yaoi/male-male art and fiction, meanwhile yuri/female-female). Get it in your head Bioware: Give people male-male romances, and the female gamers WILL come.