tug at somebody's heartstrings
US /tʌɡ æt ˈsʌm.bə.diz ˈhɑːrt.strɪŋz/
UK /tʌɡ æt ˈsʌm.bə.diz ˈhɑːrt.strɪŋz/

1.
to cause strong feelings of love or sympathy in someone
:
•
The story of the lost puppy really tugged at my heartstrings.
•
Her sad eyes always tug at his heartstrings.