IPA: /ˈhɑːrtˌrɛndɪŋ/
KK: /ˈhɑrtˌrɛndɪŋ/
Causing a lot of sadness or emotional pain.
The movie had a heartrending story that made everyone cry.
Heartrending → It is formed from "heart" (from Old English "heorte", meaning the organ that pumps blood and also symbolizes emotion) and "-rending" (from the verb "rend", meaning to tear apart). The word "heartrending" describes something that tears at the heart, causing deep emotional pain or sorrow.
Think of something that 'tears apart' ('rend') your 'heart' — that's why heartrending means deeply emotional or painful.