Debt Replaymenet

Hi There, I have given 4 lakhs rupees to my family friend for his education and some help to his personals. We were not agreed that I would seek the money back in return. Actually, My sister and he was in relationship and were to get married, but both were studying that time we had given them sometime to settle down and then get married. Later the guy was going to study in abroad and he applied for education loan in bank, when we got to know this, we offered him money to pay his education fees instead taking loan from bank, But we did not had an agreement on paper, neither my father told him that we would seek money back. Since my sister and this guy was going to get married, we thought its good deal we did. Things were going good, but when he returned to India, they had some issues and were fighting even for very small small issues, by seeing this, my father concluded from this relationship and said we dont want you both (My sister & the Guy) to get married, and after his some try they were separated. Now my sister is married (3 years back), and the guy also got married this year. The problem is, we are now demanding the money back from him for long time, but he is not eager to address it to repay. Since we dont have an agreement nor my father asked him to repay while lending him. Can we file a case against this person on a ground of not repaying the money?, by considering his financial condition is not very strong to repay it (4 lakhs in one shot). Please suggest me so that we can have our money back. Thanks & Regards