What is the origin of the idiom "shoulder to cry on" and when to use it?

The origin of the idiom "shoulder to cry on" is derived from the physical act of offering comfort and solace to someone in distress. The phrase metaphorically represents the supportive role of a shoulder as a symbol of strength and stability. It draws upon the understanding that when individuals are overwhelmed with emotions, they often seek comfort by leaning on or resting their head on someone's shoulder. It is commonly used during times of personal distress, such as relationship issues, loss, grief, or significant life challenges.