Another reason for all this drama is purely because of the fact that KiShaRa are simply being KiShaRa... Misunderstandings and them go hand in hand... You don't expect RaHi or Piddi-KD friendship to be affected if a similar situation arises.. Saalon ki dosti hai un donon ki beech... They had time to learn to trust each other...
And in KiShaRa's case, KD_-RV were just newly turned friends from frenemies and Kiya had her trust broken.. They were slowly regaining ecah other's trust and building a beautiful bond between them, It had such an impact because it was during the phase of their newly-found friendship that caused this. If they were good friends before there would't have been such a situation and tension between them..
And back to the topic which was about KD mentioning about the kiss, that is his way of defending himself.. Atleast he is defending himself instead of just hearing all their taunts and simply keeping quiet..