Why should the law care about what I do behind closed doors?

It shouldn't to a point.

Liberty is not boundless. It does have its limits.

Society sets laws announcing those actions that it deems unacceptable in polite society. If evidence appears that causes a reasonable person to suspect that illegal activity is going on, society should investigate. Of course society might find itself having to jump through hoops by adhering to constitutional law. It cannot just invade your personal space and demand to know what you're up to just because they don't like you.

Has anyone shared his wife with a friend? How was it?

But what if you're raping little girls behind closed doors? Killing gay men? Watching child porn?

The law shouldn't care (if you are a law abiding citizen) about who you take into the bedroom as long as they are consenting adults. How many guns you own. What you eat for supper. What kind of TV shows you watch. Whether you watch porn or not.

You can stand on a public sidewalk and take pictures of my house. You can't walk into my house uninvited and start taking pictures.

We now told, by Senator Grassley, that on the FBI form about the Biden bribery story, there is a Burisma exec who says he has 17 tapes of his deal with the Biden. 15 of Hunter and 2 of Joe Biden? What would this do to Hunter/Joe Biden if released?

If evidence arises that you are doing these things behind closed doors, don't you think the government has a moral obligation to investigate?

The law doesn't care about what you do behind closed doors as long as it is within the bounds of what the law allows.

Your speech is free. But if it causes malicious harm to someone, you can be sued.

Canadians went out of their way to help Americans stranded in Canada after 9.11.2001. Why did Canadians help so much the way they did? We read that Canadians don't particularly like Americans to begin with.