Well, Hotaru's pretty gay for Chibiusa (allowing for their age bracket of course), so Saturn's a fair pick too. Actually I can't think of any planets that you can't argue are gay from a Sailormoon perspective. Maybe Pluto, but even then you've got the whole co-parenting thing in the manga.
I didn't want to be Tuxedo Mask.
Don't blame you. I can't honestly think why anyone would.