If eternal happiness is to be in a perfect union with God—to be at one with him, it is only logical to want to know more about this person that we will forever united with in eternity. And who else has planted in our hearts the desire to know God, than the Lord himself.
How often do we think of the Lord as a romantic?
And yet he is the lover who lovingly leads his beloved on a journey of discovery where he reveals himself to her slowly but surely. And with every new insight he leaves behind, she will only fall more and more in love with him because she has found one more piece of the magnificent and beautiful picture of God. And while that 'picture' will be only truly be made whole in heaven, the more pieces she discovers, the clearer her vision of her lover will become. And she will yearn for him.
It is that desire and love that will blossom into full realization when she is finally united with her lover in eternity. Hence, eternal happiness.
God could of course reveal himself to us in one instant, and save us the trouble of trying to learn about him, along with the great risk that we never do... but that would take away all the anticipation, excitement and romance.
And God is infinitely romantic.
"Let us love, then, because he first loved us." 1 John 4:19