Definition
This idiom is used to express that having good intentions alone is not sufficient; one must act upon those intentions, as failing to do so can lead to negative outcomes.
He had intended to help his friend, but his interference only made the situation worse; it just goes to show that the road to hell is paved with good intentions.
Their initial plan was to save the company money, but the measures they took ultimately led to higher expenses; it goes to show that the road to hell is paved with good intentions.
She tried to give her children a surprise, but her secret plan ended up confusing and upsetting them; it just goes to show that the road to hell is paved with good intentions.