Actually, IMO, the answer it a bit more profound, but we don't need Garabandal to answer the question.
God does NOT need us for His glory or for His happiness. He is perfectly happy and perfectly glorious of Himself. He needs absolutely nothing from us. So His will to create us was a perfect act of generosity. He asks us to love Him because it'll make US happy. He knows that we can have no greater happiness than to love Him, so that is why He commands us to love Him ... for OUR good. Very few human beings ever love in a purely selfless way. When we love, it's because the object of our love makes us happy ... at least to some extent. By contrast, God's love is purely and absolutely selfless.
Now, in order for us to be able to have the greatest possible capacity for happiness, this also comes with the flip-side where if we fail to fulfill this great capacity, the accompanying suffering is all the greater, in proportion with this capacity that fails to be fulfilled. If someone had a very small capacity for happiness (such as say, what an animal might have), the suffering is far less great as a result of not attaining to that happiness. There's a far greater PRIVATION in proportionate to the capacity. If I have a 10-gallon jug and it's empty, it's now 10 gallons short of being full. But if I have an empty shot glass, then it's just a few ounces short of being full. There's a much greater privation in the former than in the latter, and that privation, translated to sentient beings, translates into suffering.
God is a perfectly simple Being, and God is love. He does not, then, have a "different attitude" toward the damned. He loves them also. But their refusal to accept this love causes them intense suffering. It is the fire of God's love that causes them to burn by their refusal of it.
This is one analogy that I like to apply, although it's at a much lower level. Let's say that I truly enjoy classical music, but then a friend of mine hates it. We're both in some class at college where we're required to attend a classical music concert. While I love every minute of it, this friend is miserable the entire time, squirming in his seat, watching the seconds tick by and counting down until it's over. Or, while I love being at Mass, someone else might hate it and can't wait to get out of there. Similarly, our DISPOSITION toward God is what causes us to either be happy in God's love or miserable on account of it. There's that story of a saint who asked God why He put souls in Hell. So, to please the saint, He took one out of Hell and put him in Heaven. That soul was miserable and asked out. He hated being there. So then the saint pleaded that God would put him at least in Purgatory. So the soul hated being there also, complaining of being in-between and neither here nor there. So, finally, God said that he could go wherever he wanted, and with that the soul dove straight back into Hell. God never sends anyone forcibly to Hell. They choose to go there.
God is perfectly simple, unchanging, and so the different experience we have of God (where he makes some of us happy and others miserable) is due not to God having a different attitude toward one vs. toward another, but with our subjective disposition towards Him. So our happines or suffering are entirely quoad nos and not quoad Deum.
This is actually one of the reasons that I dislike the opening of many Catechisms. "Why did God make me? A: God make me to know Him, to love Him, and to serve Him ..." It almost gives the impression that God is some kind of supreme megalomaniac who made a bunch of slaves to love and serve Him, and some might take it that way. And, by the way, "Love Me, or else. ... Or else you'll burn in hell." That's a very poor perspective on God that is being echoed by this question here and can lead to a very bad caricature of God in some people's minds.
God gives some of us a taste of this with children. When they are bad, we suffer not because of ourselves, but because our heart breaks to see them behave that way, because we love them. We give them commands not in order to make ourselves happy or, as they often think in their little brains, because we're sadists who want to deprive them of happiness. If I tell my children that they can't eat a whole cake every day or an entire bag of candy instead of a good meal, it's not because I want to deprive them of the joy of eating candy, but because we know that, while it might make them happy in the short term, in the long term it will make them unhappy, due to the health problems that will occur as a result. When we tell a small child that they can't play out in the street, it's not because we're these killjoys that want to deprive them of the happiness (as they might fancy) but because we know that extreme unhappiness and suffering that might come as a result of it. I might even apply corporate punishment. If I see a young child attempting to put metal objects into an electrical outlet, I'll slap his hand, not because I wish the child to suffer, but because I want to PREVENT him from sufferinng. But his pea brain doesn't understand what we understand, since we have a more informed perspective. Thus also, God gives us the commandments not because He wants to spoil our fun, but because He knows that engaging in these activities will NOT make us happy, but will make us miserable instead. People who wish to violate the 6th commandment, for instance, resent that God wants to get in the way of their fun, not unlike how the child who wants to eat cake or candy all day believes that his parents want to spoil his fun. But God knows the terrible long-term effects violating these commandments will have on our happiness. So if we know so much more than an ignorant child, how much more does God know that our pea brains can comprehend? This gap between our knowledge and wisdom and that of a young child is absolutely nothing compared to the gap between what God knows and understands ... and our capacity to understand it.
So why does God allow suffering? That's another question often asked. Why does a parent inflict suffering upon a child? ... in order to correct them, toward their ultimate happiness, even if in the short term it makes them unhappy, at a much lower level. So, there are some people who actually have a genetic defect that prevents them from feeling pain. They are often at great risk of serious injury. They can have their hand resting on a hot stove and not notice the pain, and therefore sustain serious burns. Similarly, if we get physically injured, say if we sprain and ankled or break a bone, we experience suffering, but the suffering actually alerts us to the problem and deters us from greater injury, causing us to protetect the injury. Thus we might limp, in order to prevent putting our full weight on it, and thus injuring ourselves even more. If we felt no such pain, we would risk much greater injury. It's similar with emotional or even spiritual suffering. It's all designed toward our ultimate happiness, and to deter us from behavior that might cause us even greater harm.
Or, another way to look at it. Someone falls off a tall building and dies. Why did God make this thing called "gravity" [cosmological debate aside]? Well, imagine what it would be like without it? We'd all fly off and could never have a stable existence. So these "laws" God puts into place to keep order, well, they also sometimes have side effects. Similarly, when we break the commandments, those have side-effects. They're put into place to keep everything well ordered, and ignoring them will have serious consequences.