I think a built in slider or "preference" option would really be best here, I don't think those who want, or don't mind autonomous homosexual relationships should be forced to download a mod to enable it (as if homosexuality is somehow more "deviant" in the game than heterosexual *rollseyes*), any more than I think people who don't want their active sims engaging in sexual activity or relationships opposed to their preference (If they have one) should be "forced" into it.
Now, with that being said, I definitely don't think sims in the active household should be getting into autonomous relationships with ANYONE, regardless of gender. It should be 100% player initiated for anything past flirting.
