They are real soulmates...
See, how a sudden idea struck phool's mind to save her beloved Pratap(just the way Ajab gets ideas in hard times when no one is able to think anything)
Moreover Pratap has also started feeling that Phool is his shubh chintak and I think that before siting for the wedding he would realize that it has always been Phool who thought about his welfare, selflessly and purity in her hart and has always saved him from the dangers.
Then he would say Ajab : Ajabde, hum aapse vivah nahin kar sakte. Aaj humein yeh samjh aaya ki humarein liye Phool hi sabse upyukt ladki hai. Humein shama kijiyega par hum aapse nahin kar sakte vivah. Kasht ho raha hai humein humeri Phool ko balidaan dete hue dekh. Hum unhi se vivah karenge. Aap toh humari mitra hai na isliye humain purn vishwaas hai ki peechle baaron ki bhaati iss baar bhi aap balidaan ki murti ban apne dono mitron ke liye balidaan de paayegi hai na?"
Ajabde will readily agree has as her only dream was getting fulfilled of PraPhool getting married. Then Praphool will get married happily. And Ajab would dance in their reception.
I am eagerly waiting for this day!