Happiness is a great thing. Who doesn't want to be happy? There is something obvious and universal about this. If someone wants to be unhappy, if someone seeks out suffering intentionally, depending on the circumstances we would think there is something seriously wrong with them.
Is there such a thing as wanting to be happy too much? Yes, I think so. I believe in America, which with all of its poverty and violence is still more affluent and safe than most other places in the world (and that is an understatement), happiness has become something of a golden calf. Happiness becomes the goal of life... the measure of the worth of a life, the final evaluator of your decisions, the benchmark of success... and therefore anything which disrupts that happiness, such as evil and suffering, has no value and only serves to destroy your life.
And that is what many of us implicitly think. Evil and suffering are not life. They take away from life. And thus, when evil and suffering hit home, and they will with even the best of us, we crumble. We lose heart. We lose faith. We feel cheated and wronged. We feel that life has lost its meaning. We cannot see that the suffering has an ordained place in shaping our life, our story, our touch on the lives of others, even if it is not the way we want or had planned. Happiness must be found, and this person or situation or event has screwed it all up!
If this is all you have, if there is nothing beyond this, then this is really your only shot to enjoy yourself, so you had better take it.
If happiness in this life is all you have, why give that up? Why be a hero? You might lose your one chance to be happy, after all.
Even though we know that type of thing is cowardly and selfish and we instinctively know that sacrifice for the good of another is of far better virtue, people still use happiness as the baseline for even their most life-altering decisions. Take the high divorce rate, for example. While I would certainly agree that there are many cases where people are better off being separate from their spouse due to things like infidelity and persistent abuse, how many marriages and families are offered up to die on the altar of our personal happiness?
Here is the crux of the matter. Happiness is a good thing. But when your life goal is happiness, when the only thing that makes your life a "good" life is your own personal happiness at any given moment, then you will find yourself unable to cope with real life. Things like right and wrong start to slip back into the gray. Sacrificing yourself for the good of others becomes the stuff of romantic fairy tales. Finding meaning and truth, and for that matter finding God, in the midst of suffering becomes a very distant and unrealistic and arcane sentiment.
And in the midst of all of this you may find what your character is really made of. When evil and suffering hit and your life begins to unravel, suddenly you may catch a glimpse of the fact that a large part of why you did any of the good you did was not for the goodness of itself, not really for others, and not for God. You did the good you did largely with the expectation of controlling and keeping life the way you want it, revealed by the fact that you feel cheated by God and the universe because you thought there was some kind of unspoken deal: I'll be good and you will keep me happy and make my life go according to my wishes.
The cruelest trick of all is that the pursuit of happiness is a lost cause. Jesus taught us that real happiness is never found in itself. It always comes as a byproduct of the pursuit of something else. Pursue happiness -you never find it. Pursue righteousness and the kingdom of God -you get happiness, blessedness, joy thrown in... not because you leverage God into giving you the kind of life you want but because you discover happiness in righteousness for itself and in God for Himself in spite of the circumstances around you.
If you "just wanna be happy," you will find that you go through life whining, because life will seldom go according to plan.
If you truly "just wanna love God and love others," you will discover that a kind of happiness follows you, a happiness and contentment that can live quite easily alongside sorrow and pain.