Happiness is not an outcome. It must be your resolution
Some people worry what will happen to everyone once they are no more. When they do, take a bucket filled with water to them, request them to dip their finger in the water and remove. Then ask them if that created a hole in the water. Just like no hole is created in the water and the water adjusts back to normality, similarly, when we pass away, the existence also adjusts itself.
Nothing in this world stops due to anyone. The wise thing is to enjoy life while you are living in the present. Everyone is independent to be happy if they want to be. That is why happiness is not the outcome of something. Happiness must be your resolution. One who truly wants to live in joy cannot be given grief by anybody.