They were a very successful pair
It began with Raja Hindustani
Aamir Khan wanted Juhi to play the female lead and went to her house to personally narrate the script for her
Dharmesh Darshan too went with Aamir and Juhi sounded impressed and gave her oral OK to the dates
However a few days later Aziz Mirza, a very close friend to both SRK and Juhi Chawla invited her to dinner and offered her YES BOSS and she couldn't say to no to SRK
So she accepted YES BOSS whose 8 weeks clashed with Raja Hindustani
Dharmesh Darshan was OK with the shoot schedule modification but Aamir Khan was FURIOUS
Aamir saw SRK as a rival and felt he should have won the filmfare for Rangeela over SRKs win in 1996.
He felt Juhi had insulted him by not turning down SRK and rather turning him down
He refused to allow the modification and allowed instead - Karishma Kapoor to play the role which was a massive break for her career
Juhi was not the first choice for ISHQ
Madhuri Dixit was
Karishma Kapoor was
However Karishma Kapoors mother Babita refused to allow her to act opposite Ajay Devgan whom she felt was a second tier actor back then
Madhuri Dixit unfortunately had Vinod Khanna visit her personally to request her to do Mohabbat with his son Akshaye Khanna (Forcing the removal of Actress Deepti Bhatnagar from the film) for enhancing star value and that was a BIG THING
So Indra Kumar had to rope in Juhi Chawla and Aamir was TOO PROFESSIONAL to object though he slowly began to recover his pride
Meanwhile Kajol was roped in because of Ajay Devgan as a friend back then (Friend - Lover phase)
During the shooting of ISHQ , there was a major ego issue
Aamir Khan devoted his full time to one film and kept his dates for ISHQ only. He wanted a handful of retakes including a scene where he mimics Sadashiv Amrapurkar (a cringe scene where he applies layers of brown color agent and a wig)
Juhi unfortunately didn't turn up for two days and the entire shoot was wasted with Aamir Khan sitting there the whole day
This was the last straw and Aamir decided NEVER TO WORK WITH JUHI AGAIN and never did
Different versions
The version was Juhi had flown to Switzerland to shoot a few dance moves for a song with SRK for Yes Boss to wrap the shoot and for Visa reasons she had to fly down without any delay
This angered Aamir Khan
However later on , Juhi said the reason for why she didn't come on sets for two days was because Aamir pulled a prank on her and she was so upset she decided to not come to the set for 2 days
I don't believe the second version
Actresses were never the kind to miss a days shooting unless it was an SOS
Mohan Babu is known to have physically slapped Sakshi Shivanand twice for a 3 hour delay
Plus Aamir is ultra professional and his pranking in sets is highly unlikely as other actresses like Madhuri have never made such a claim, always calling Aamir professional and a perfectionist
Aamir has EGO
So likely the first version is true