I'm sure there's a great deal many positives which adultery offers to society.
You said that "the government has no right to regulate behaviors unless there is a great deal of societal interest in the law."
Society has an interest in marriages continuing as families provide the building blocks of our society. Thus, according to your statement (which you seem to have a bit of trouble remembering from post to post), the government would have a right to regulate behaviors which would decrease the likelihood of families continuing together.
So if my dad cheated on my mom, the best thing for all of us is if he was thrown into jail?
I know it's hard to switch off the WOD mentality, but no one said anything about jail.
And, of course, you're picking apart the smaller pieces of my statements while the big picture remains. Namely, you tried to make a distinction between illegal forms of sexual behavior which the government could regulate according to you and homosexual behavior (which the government cannot regulate according to you). That distinction is nonexistent. Thus, in your scenario, the government has no basis to regulate any sexual behavior at all, your protestations to the contrary notwithstanding.