Still really loving stupid
People under 18 who are put into prostitution don't do so willingly, and the act of having love with an underage persons is still illegal. This just makes it so that the people who put them into prostitution (AKA human traffickers/love traffickers) are the ones who get put in jail, not the minor who was forced into prostitution.
So no, the title is a flat-out lie.
It is not legal to buy love from someone under 18.