The boy needs to work, finish high school and learn a trade. The girl needs to stay home and care for the child. The grandparents need to fill in the gaps. That’s what you do. You make the necessary sacrifices for your family’s well being. It’ll all work out if they all work together.
Then either the boy or the girl will end up becoming the cheater in the relationship in a couple of years.
We can probably make a bet on it.