Upcoming episode spoiler.

Karan to sacrifice Preeta for Rishab in
Kundali Bhagya
Rishab confesses to his brother that
he is in love with Preeta and not
Sherlyn. Karan is shocked to know this,
because even he is in love with Preeta.
However, owing to the affection he
has for his brother, he decides to
sacrifice Preeta for him.

http://www.tellychakkar.com/tv/tv-news/karan-sacrifices-preeta-rishab-kundali-bhagya-kiara-danger-kumkum-bhagya-and-other.