It was a bit like Romeo and Juliet.
They loved each other, but their families were enemies. Because of that, they wouldn't let them be together. All because she was a Potter and he was a Malfoy.
But they still tried to be together behind their families back's. They would sneak out at night on the grounds at Hogwarts, mostly down to the lake. She had already managed to steal her father's old Invisibility Cloak from James, who presently had it.
She would go to the Slytherin common room in the middle of the night, and he would meet her there.
It took years and years to convince their families. They still did not like each other. Her mother was the first to realize that they really did love one another.
They two families still disliked each other. A lot. But they both eventually came to see that these two teenagers were in love, and they tried to get along, for their children's sake.
It was a bit like Romeo and Juliet...Except Scorpius Malfoy and Lily Potter got their happy ending.