-Except the fact, that for a marriage to even register as a marriage, the consent from both parties is a REQUIREMENT. The law is already present.
Your suggestion is a law/modification to ANOTHER law to prevent an act from happening, which already is outlawed in the present framework.
-Secondly, what about unwanted teenage pregnancies, what about abortions, what about partners manipulating the other in to getting what they want ... are these not problems western teens have to face? Yet still, the age of consent is 14-16 years across west,
shouldn't you take a good hard look in the mirror, apply your 'solutions' unto yourselves first before bringing your "awesome strategies" in another culture ... just a random thought