Here’s the problem. Happiness (I’m not distinguishing it from joy) is an experience of the soul, something outside of me to be desired. So to desire happiness is not the same as desiring a cheese biscuit at Red Lobster, nor the same as desiring forgiveness for my sins. The biscuit and the forgiveness are desired because they make me happy (yes, yes, vastly different degrees of happiness). But happiness is not desired because it makes me happy. It is my happiness.
You see the problem. Happiness, and things that make us happy, are not in the same category. But we can speak of desiring both. And it can be confusing.
When I say I desire happiness, I mean, “I want to be happy.” But when I say, I desire a biscuit, I do not mean, “I want to be a biscuit.” Happiness is not an object to be desired. It is the experience of the object.
So it may not be idolatry to say, I want happiness more than I want any other experience. God is not in the category of “experience,” and so you are not ranking him. You are (know it or not) preparing to find him.
Idolatry is not wanting happiness supremely. Idolatry is finding supreme happiness in anything other than God.
So there are two ways to speak of seeking happiness. One is to say we seek the experience of happiness. Another is to say we seek what will give us that experience. If you keep this in mind, you will not call someone an idolater who wants happiness above all experiences. But you will know what to ask him next.