A man said to Imam Sadiq (A.S.):
“When a person says to me: ‘I like (or love) you.’ How do I know that he is telling the truth?”
The Imam (A.S.) answered the man:
“Examine your heart, if you like him then he likes you. Look in your heart, if it refuses your companion then one of you has done something.”
Al-Wafi v.3, p. 106
Same question i keep asking myself! Beautiful answer by the imam..