The title song of the Ranbir Kapoor-starrer is crooned by Arijit Singh and penned by lyricist Amitabh Bhattacharya.
Pritam says apart from the title track, which was finally selected for the film, he had composed another song which went on to become "Tu Jo Mila" from last year's blockbuster starring superstar Salman Khan.
"I had composed two options for the title track. One is the same title track 'Ae Dil Hai Mushkil', as you hear it now. Since the choice was made, the other track I used it in 'Bajrangi Bhaijaan'.
"Later, when this came in (ADHM title track), that song became 'Tu jo mila' and it was going immensely well in 'Bajrangi Bhaijaan'," he said.
The upcoming romantic-drama also stars Anushka Sharma, Aishwarya Rai Bachchan and Fawad Khan.
There are reports that Ranbir plays a singer in the film.
The composer was lavish in his praise for Ranbir, for
whom he has previously given chartbusters like "Yeh Jawaani Hai Deewani", "Barfi!" and "Azab Prem Ki Ghazab Kahani".
"I messaged Ranbir multiple times saying that in my life I haven't worked with an actor like him and that his talent is unparallelled. It is really brilliant for an actor to be able to hold a song for nearly 45 seconds, carry forward a full mukhda in one shot and express the entire emotion just through the eyes," Pritam said.
The 45-year-old "Dilwale" hitmaker said though one doesn't associate "intense" songs with a Johar film, "Ae Dil..." demanded that kind of mood.
"The film is about unrequited love, so songs actually depend upon the situation, characters. Though we don't generally associate pure romantic melodies with Karan, this movie is much more intense."
Pritam said the album, to be out by September end, will have seven tracks and is a "mixed bag of intense, romantic songs and fun songs.
