I knew this would show up here eventually.
While I do not agree with child marriage, and cannot condone it, until fairly recently this was the norm throughout the 'civilised' world.

To those who criticize, also known as 'fucking do-gooders' (fdg).

Is everything in your country perfect? No more rape, no more incest, everything in your particular part of the world is just peachy, a regular paradise?

I know the answer to those questions is NO.

Then I have a suggestion for you.
Fix your own problems before you go meddling in others affairs. You a far more likely to make things worse by your interference. Those people will work it out eventually if you leave them be.