I should probably clarify.

I wasn't meaning to say "Look at this case, it's obviously about control".
I was using it as a reference for what image had lead me to ask the question in the first place. Then in extension, I noted it as a possibility, but was also asking out of curiosity if people thought there was more to this case specifically, and if people could give any logical reasons for it since the original group wasn't really saying anything outside of "Just because" which I never accept as a legit reason.

I like the answers that's been coming here though, and they probably are what goes on in a lot of people's heads.
In extension, I guess the "It's only me" thing is also part of why Monogamous relationships appeal to so many people and got started in the first place among us, even though we are a polygamous species if we simply followed our hormones.