Give the U.S. 20 years and the Left will have succeeded in lowering the age of consent down to similar levels. It will be considered a human rights issue and if you disagree with adults marrying children you will be branded a bigot.
Obama pointedly met with people like this when he was in St. Petersburg. Some Russian "Youth Human Rights" group (I can't remember the exact name) which advocates for the sexual "rights" of LGBT minor children.