Create chemistry between them.
Then make the boy fall in love with another girl.
Let that issue be converted into child marriage is bad and not the boy who simply wanted a sophisticated girl to flirt with.
Let the sophisticated girl turn into a frustrated woman with a past.
Make the boy disenchanted with the sophisticated girl.
Meanwhile let the first girl go for a second marriage.
Let the boy come back and want the first girl back at any cost.
Introduce another village girl for the boy.
While the boy had a brief engagement drama with one more city girl.
Make the city girl the worst possible female on earth while making the village girl, the epitome of all virtues.
Let the boy tie the knot with the virtuous village girl.
Make her pregnant and make her mahaan to go through a risky life threatening pregnancy.
Make a meaningless track for the new hero to search for his real parents.
Create a father for him out of the blue.
So that he can have 2 sets of parents and enjoy life to the hilt.