Many practitioners believe that the cause of suffering is attachment. Actually, the Buddhist sutras make it clear that the cause of suffering is ignorance. Attachment is clearly one of the afflictive emotions mentioned and some scholars believe that the reference to attachment was a shorthand reference to all of the problematic states of mind.
Although the analysis of ignorance as the cause of suffering is complex, in summary it means ignorance of our true nature, ignorance of the nature of your awareness caused by the distortions of a dualistic perspective.
To put it simply, when you believe all that you are is a mind and body and perhaps even a soul with you "in here" and everything else in the universe "out there", you will be forever locked in the conflict of you versus everything else in the universe as separate from you and that potentially can affect you.
Your dualistic belief in a separate self as the nature of your existence and awareness is the primary ignorance and the cause of suffering.
When you experience and truly know that it is not true, suffering ends. It is not that you do not experience pain or sadness or anger or any other of the countless things that hurt us, it is just that you know them to be just mind objects, arising like all else in your awareness, and that in the universal scheme they are not real. They are fleeting and impermanent, like images on a screen. And in the same way that even the most horrendous image cannot distort a screen upon which it is projected, nothing that arises or happens, absolutely nothing can ever affect what you truly are. Not that feeble bag of skin and bones and brain tissue you think you are, but Emptiness, the knowing, experiential quality of the universe itself that you and every living being is and upon which the universe itself manifests.
So when you encounter a religion or philosophy or way of life designed to lessen or end suffering, ask what it is talking about. If it teaches you how to be a better person or to show compassion to others or to take better care of yourself and the planet, that is wonderful and worthy of your time. But that does not end suffering. That teaches you how to remove or lessen or avoid the events or conditions that hurt you or others or the world and cause pain or the other endless unpleasant emotions or feelings you can experience. Your potential to suffer remains however, waiting for the right event to arise. And they do, endlessly.
Only when you know, only when you learn, only when you finally understand what you really are, will the ignorance be washed away and you will see that suffering, like all else, is not real and cannot reach you.
If this posting is of interest to you, please read the earlier entries regarding emptiness, non duality and no self and particularly "What Are We Really?". All of this may sound too poetic and metaphysical if you do not.