During the summer of 1997, Princess Diana flew to Lahore with Jemima, on Jemima's father's private jet where she reportedly met with Hasnat's strict Muslim parents.
But despite this, the secret relationship did not move forward and the couple ended their 18 month relationship.
"I think Hasnat was very much in love with Diana, but had really reached the end of his tether because Diana pushed him and pushed him and pushed him to go public and say we're a couple, and he wouldn't," royal writer Tina Brown said in The Last 100 Days of Diana.
"So she gave him an ultimatum, either we go public or this isn't going to happen."
Khan himself spoke to the Daily Mail in 2012 remarking: "Even after two years, the relationship wasn't leading to a meaningful progression or conclusion and that was the main stress on both of us."
Diana and Hasnat met at London's Royal Brompton Hospital when Diana was visiting a friend's husband recovering from heart surgery.
The two embarked on a top secret relationship since the princess was constantly hounded by the paparazzi and Diana's former butler even revealed he used to sneak Haznat into Kensington Palace in the boot of his car.
"I would bring him into Kensington Palace in the boot of my car or underneath a blanket in the backseat of my car," the royal butler said on the documentary.
"The police never stopped me and I'd take him off in the back entrance. From there on their romance blossomed and they met him on dates outside of the palace too."
Following their split, Diana went on to date Dodi Al-Fayed with many suspecting that she did so to make Hasnat jealous.
She died not long afterwards in August 1997 and her friend Richard Kay said in The Last 100 Days of Diana that Hasnat tried to reach her that night, but was unable to get through.
"I think he was worried about her. I think he was worried, as were a lot of her friends, about what she'd got herself into."
"He [Hasnat] said to me, 'Maybe later in the summer, we'd have got back together again.'"