The show is full of promiscuous characters, but I understand his complaint. Still I think it can be argued that while Loras was deeply in love with Renly that doesn't mean he never had sex again; lots of people lose their loved one and have sex a few months later.
I was actually more disappointed with the "Loras the bride" treatment during that scene with Sansa. It was funny but it was also a clear stereotype, and I don't see why the writers decided to go that route. The majority of the gay characters in Martin's books are similar to Kima or Omar from The Wire, although there are a couple of the more stereotypical types (Renly comes to mind, but even he participated in tourneys and was considered a decent fighter). Loras may dress flamboyant but he is arguably the third or fourth best warrior in the entire series, and is well respected. He seems like a petty child thus far on the show.
Chalk it up as another area where Spartacus is superior. Probably the best, most touching relationship on the show is between two dudes - both of whom are great characters. Not simply because they're badasses, but because of some impressive character development and drama (especially last season).
