it is not sudden. main to kab se keh rahi hoon k confession hone wala hai.
according to that symbolice balloon scene, karan has to reject preeta's love first "ye apna pyar kisi aur ko de dena". preeta ka dil tootna zaruri hai.
then her heart (balloon) goes to rishabh's car.
actually prirhvi's revelation is a major event in current storyline. it will lead to so many things.
karan saved preeta from marrying prithvi thats y..... preeta puri tarah pighal jaye gi karan k liye. karan ne usko hamesha prithvi ka sach batane ki koshish ki. aur us se shadi karne se bachaya.
revelation of prithlyn's affair to preeta is also very significant in context of RishTa. i will make a separate post on this.
Oh OK. I didn't know about that scene. But now it does make sense😲. You do analyse deeply for this show which on surface doesn't seem to have much story 😆