Once upon a time, in a certain town there was a coffin maker who opened and was running a store where he sold the coffins he made himself to the customers in the neighborhood. The popuplation in the town increased day-by-day.
I don't think happiness and suffering can mix together. The absence of suffering is happiness and likewise the absence of happiness is suffering. You can be in pain yet you are still happy. Pain per se is not suffering. But you can suffer due to your pain. You can also suffer without pain.