You say of that friend of yours that he frequents the sacraments, that he is clean-living and a good student. But that he won't 'respond'; if you speak to him of sacrifice and apostolate, be becomes sad and goes away.
Don't worry. It's not a failure of your zeal. It is, to the letter, the scene related by the Evangelist: 'If you wish to be perfect, go and sell what you own and give the money to the poor' (sacrifice), 'and then come, follow me' (apostolate).
The young man also abiit tristis, went away sad; he was not willing to respond to grace.