Harrasment by individual on account of marriage

Hi, It's regarding my sister her relationship talks for marriage was under process with one individual since June 2018 and they were talking to each other on phone and WhatsApp, even the boy has met my parents but whenever we used to ask that individual to organise a meeting with parents he used to come up with excuses that right now somebody is not well or I am busy with some projects this continued till March 2019. Prior to this we met his mother once in August 2018 that time her response was not positive for relationship and she said she will let us know about the status but she never responded after that and her son he was assuring us on regular basis that he is going to convince his mother but he need some time, we agreed onto it. Meanwhile he has asked for financial help from my sister several time that we have given all the time and he quoted that he doesn't know how to drive, so my sister used to take him to various places for his work related duties and even she used to come all the way from Himachal alongwith parents staying in hotel and spending money for his food outside, on regular basis. Now in April after pressurising the individual he is saying that my family is not agreeing, slwe should end this relationship and talking abuse to my sister and harrasing her mentally by calling her at odd times. He wasted our one year with a hope but now at the end he just wanted go away just like that. Request you to please guide us what legal action we can take against this individual. Thank you