Prithvi and Preeta is Jodi with not that bonding as it is shown Preeta for her happiness of her family is said yes to Prithvi and that is somewhere the reason there chemistry is seen to be not that strong. Whenever they are seen to be together Preeta tries to avoid him in some way. Where Prithvi tries to have romance and bonding but doesn’t stand to it.
On the other hand, talking about Preeta and Karan they both have the best chemistry. They are shown as best friends but their chemistry is so superb that we can say the majority of the audience of Kundali Bhagya is due to the chemistry of Karan and Preeta. Karan and Preeta have their sweet and spicy love story roping the audience. Their bonding and chemistry are so loved by the audience that they are known as ‘PreeRan’ by their fans. They are seen arguing and fighting each other but there also their chemistry is on fire. Karan and Preeta have so strong chemistry that sometimes people consider them as a real-life couple. Be it spending time together, arguing on small things, catching those small meaningful moments or even sneaking up on each other, Karan and Preeta have the best bonding ever.
So obviously the chemistry that creates fire in the show is but for sure Karan and Preeta. Karan and Preeta have the best chemistry rather than Prithvi and Preeta.