Why did Hyde commit suicide?

Hyde did not commit suicide, or at least we never learn of his true end. The novel ends with Jekyll's confession and letter of truth, in the letter, Jekyll knows his own life is ending....... that Hyde will have complete control. Thus, we might see Jekyll's actions as a kind of suicide...... giving his own life up for Hyde, not so much because he wants to, but because he no longer has control.

Will Hyde die upon the scaffold? or will he find courage to release himself at the last moment? God knows; I am careless; this is my true hour of death, and what is to follow concerns another than myself. Here then, as I lay down the pen and proceed to seal up my confession, I bring the life of that unhappy Henry Jekyll to an end.