Chronic illness, difficult marriages, losing a child—doesn't God want me to be happy?
God definitely wants you to be happy long-term and infinitely, and deeply now in and through those circumstances.
What then shall we say to these things? If God is for us, who can be against us? He who did not spare his own Son but gave him up for us all, will he not with him freely give us all things? (Romans 8:31-32)
That's saying that since God paid the infinite price of his Son for you, will he not then surely carry through in providing everything you need?
And then it goes on to say, "What shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness"—I mean, these are hard things!—"or peril, or sword? As it is written, 'We are being killed all day long'" (8:35-36).
So you've got persecution and murder of Christians. And then he says, "No. In"—In—"all these things we are more than conquerors through him who loved us."
What I think "more than conquerors" means for your happiness is that a conqueror has his enemies lying subdued at his feet. You've got distress, famine, nakedness, peril, sword, persecution, and there they are, conquered at my feet. More than conquerors means they're not just at my feet. They are serving me. They're not just in chains in prison. They are serving me. My persecution, my famine, my nakedness, my loss—as painful and as tearful as they are—are my servants. God works them all together for my good.
Now that good that he works in and through them is the foundation of my happiness. It isn't the circumstance. There's plenty of tears. Jesus was "a man of sorrows and acquainted with grief." Paul says, "Sorrowful yet always rejoicing."
I think Paul was always crying and always happy. How could he not be crying? He was so beat up. His back must've looked like a hunk of jelly most of the time because he had these five-times-thirty-nine lashes beat over his back and then healed in all kinds of gnarly ways. So this man lived with a thorn in his flesh, probably in his back, in his eyes, in his mind. And he had enemies all around him. And he said, "Rejoice in the Lord, and again I say rejoice!"
So yes, God wants you happy. But he doesn't do it with circumstance. He does it with himself. He does it with the gospel. And he does it in and through circumstances.
This is a call for faith—huge faith—that God is good, God is for us, and God is using all these things for our deep happiness now and our perfect, unsullied happiness forever in the age to come.