The Qohelet is still perplexed by life and how things are distressing because there is no way to tell that what happens to the righteous is any different than what happens to the wicked. Yet he admonishes his readers still to the idea that God knows what he is doing and he has a plan. What is good to do for sure is to eat and drink and enjoy life with the loved ones God has given you--for "God approves of this!" Wisdom will have its limits, but in this at least, you kind find a daily peace and enjoyment.