Why

I think it' because the uke refuses to be locked up amd he can leave whenver he wants , he simply can't be someon's thing that's why everyone wants to have him to themselves
He's like the forbidden fruit.

So the harder it is to reach him the more they are willing to lock him up

Yup
This thing exists in real life y know

For real?

Well it does exist but not like wanting to lock someone up , it's like you want them to be only yours but you cannot