I know this is a sensitive topic and vex go plenty, but is there any country in the world which has an exceedingly high number of single female celebrities like Nigeria?

I don't know of any although I stand to be corrected if wrong.

Is there a reason why their contracts require them to remain indefinitely single, unlike places such the US, Britain and the rest of Europe plus the rest of the world where celebrities date, marry, have kids, etc even if it's in the public eye.

It also goes against Nigerian culture but let's ignore that.