I play generationally, I like playing young adults most, so my Sims remain young adults through Marriage and raising their kids. Once the next generation is ready to take over, that is when this generation celebrates their happy ending, by being set free of my control and finally leading the rest of their lives entirely on their own, getting to make their own decisions. My new generation still interacts with them, they are family after all, but they no longer have a task master to control their lives, they are free.