Absence makes the heart grow fonder means -

• PROVERB
Absence makes the heart grow fonder. 
MEANING
Being away from someone or something for a period of time makes you appreciate that person or thing more when you see them or it again. 
EXAMPLE
“I used to hate going to my aunt’s house, but now I kind of miss it. Absence makes the heart grow fonder.”

Source: Cambridge Advanced Learner's Dictionary.