That occurs at the point allowing a behavior starts diminishing the quality of life for everyone. Libertarians consistently support legalizing behavior that has or will do just that.
How does what one practices in the privacy of a bedroom infringe upon your ability to L L and PH? As I said, I argue often and long that spending billions of dollars on HIV is wrong because it is a disease of CHOICE and the personal responsibility of the afflicted almost always. Public displays infringe upon my ability to enjoy public areas and I oppose that, from either side of the coin. I got banned for arguing that the LEGAL private behavior of individuals should not preclude them from service and that any sexual activity between soldiers is prohibited and should be enforced. I also argued that the best reason to deny gays from serving is that they will become a protected class with a card to play as so many soldiers play every day. For that, I am banned?