You study hard, you land the best job.
You land the best job, you're happy.
You do well on the job, you become CEO.
You're nice and loving, you end up with a good partner.
But as you move along, you realize that the life you envisioned for yourself is probably an illusion. And illusions are the only place where this vision is perfect. But snap out of it and come to reality you realize that life isn't all pinkish!
You might be with the person you love but that doesn't mean you don't have days when you can't stand their voice! You might be progressing with you're career but that doesn't mean you're satisfied. You might even be happy with your job but that doesn't mean there isn't this one person who just kills your mood at the office. You might be good, decent person but that doesn't mean you're appreciated! You might be sexy but that might not mean you're loved! You might be a good friend, but the doesn't mean the friendship will last.
There is always a "BUT" to the happy story... and in all fairness, this is life. It can't all be cheerful and happy. It can't always be perfect... in fact we know the minute we start to grow up, that perfect doesn't exist!
It's probably not as dramatic, life isn't that bad! However... sometimes you wonder, when does it go right? Or does it ever go right? When do I just relax and enjoy the moment... When do I smile without the back of my head reminding me of some problem of some sort! And especially as we grow older we, the stress of realizing that the time of turning this illusion into reality is decreasing is what frustrates you even more. Or perhaps its not too late because you can always change your life, but rather you've expected certain years of your life, your youth, to go differently.
And maybe this is why it is called and illusion.
"BUT" that doesn't mean that we stop closing our eyes a few minutes before we sleep and dive into the utopia we dream of. In fact it's the hope that this illusion may one day become a reality is what keeps us going! The fact that "BUT..." can sometimes be used in a positive light is what makes this illusion even more beautiful.