Considering a spouse can command a demon to leave their significant other by referring to their exclusive rights to their husband/wife; kinda yeah.
If you ever have to use this, do note that if whatever sin let the spirit in isn't settled, the entity will return and be more difficult to deal with.
Generally it's a wash. They are both kids and therefore not fully accountable for their actions. It would probably depend on the jurisdiction though, so results may vary.
Whenever there is one man and multiple women in the judeochristian scriptures it's described as 'one was loved, one was hated (disregarded, ignored.) Humans have a limited bandwidth; we can take care of one intimate relationship adequately, but add one or more additional intertwined...
There are metal conditions that can account for this actually. OCD; if it manifests as avoiding mixing things unnecessarily; can lead individuals to be extremely reticent about sexual relations.
Please don't; Mao already tried that, the effects of the extermination of the Eurasian sparrows combined with the lysenko-esque agrarian policies implemented around the same time starved at least 40 million. While I get it's a joke, just thought an FYI would be good here.
I've slept through a sonic boom, numerous thunderstorms, and multiple earthquakes; some people can sleep through anything. Granted I have trouble falling alseep in the first place, but that's a separate matter.