I have a feeling looking at the Precap and Sagar's expression that he may soon realize that he does not really love Kaveri, he may feel its just a childhood bond a deep friendship that he has with Kaveri, and that he loves Ganga, but may not be able to get out of the engagement with Kaveri due to family commitments.
Kaveri may first realize that Sagar loves Ganga and not her and she may tell the family this.