Regarding refusing the marriage by boy side

( hindu in religion ) Two months ago, a military family's boy marriage proposal came in my house for my sister. he's also in army. His family demanded to see the girl . We already told them that we will show our girl only one time so you should see her when the boy will come but they refuse it and said that the boy will agree on his family decision so they will decide not the boy. So agreed on that and did a program in which 18 members of boy's family came to see the girl. Then they like her and did the pre- wedding rasam godh bharai. And said that they accept her as their daughter in law and in that program that boy also talk to girl in video calling. From that day onwards boy's family and the boy started to talk to girl daily on mobile. And then the boy came on holiday in his house and put said that he wanted to meet the girl as a date before marriage so agree . After date at night his mother called us and refuse the marriage proposal and said boy didn't like the girl.