Tom Parker and Kelsey became a pillar of strength and unity during the weeks and months leading up to his tragic death in March 2022.
In his memoir, Tom revealed how the pair met, and their tumultuous first year that would become the start of a lifelong love story.
The couple first laid eyes on each other in a West London nightclub in 2009, when Tom was 21 and Kelsey just 19, and their connection was instantaneous.
Tom wrote: "Apparently, Kelsey told one of her mates, 'I’m in love with him'. It was literally love at first sight.
"I asked her name so I could look her up on Facebook. At the time I thought that was the cool thing to do, but she looked at me like I was mental.
"I told her I was in a band and, luckily for me, she told me her name."
But that wasn't the only faux pas Tom made during their less-than-fairytale first meeting, as he revealed he had mistakenly kissed another woman, thinking it was Kelsey.
"Later that night I was paralytically drunk, kissing this girl who I believed to be Kelsey," he said.
"I soon discovered that I’d actually been with a totally different girl, who I had somehow managed to mistake for her.
That gives you a bit of an idea of the state I was allowing myself to get into during those early days of living in London with the band."
The next morning, desperate to find the girl who had stolen his heart, Tom sent a text to the only Kelsey he had saved in his phone - which turned out to be a guy he knew from back home in Bolton and not the enigmatic woman he had met the night before.
"I’m thankful to say that somehow, despite these embarrassing episodes, we did end up together," he revealed.
"We had such an instant connection, I knew she was my person immediately."
Despite their incredible bond, their early days as a couple were far from smooth sailing as Tom struggled to commit.
"I was quite s**tty to her during our first year. I felt as though my commitment to being part of a rising boyband meant that I was unable to be in a relationship," he admitted.
But despite rocky beginnings, the pair went on to form a relationship envied throughout the celeb world - and Tom thanked their early meeting for helping them to stay grounded, even as he shot to fame, claiming they've 'remained the people we always were'.
Tom was diagnosed with an inoperable brain tumour in October 2020, when Kelsey was 35 weeks pregnant and in the midst of the Covid pandemic.
Tom's memoir details how Kelsey stayed strong even in the face of all this adversity, and helped him through his darkest moments.
She was even there to offer advice when the pair received the terrible news of his stage-4 cancer, telling him not to ask doctors how long he had left to live.
"When I was first diagnosed, I would have found out the prognosis, but Kelsey and my brother Lewis stopped me." he revealed.
"I needed to be able to live with hope and they wanted to protect me from anything that would have damaged that.
"Whatever they might have said that day, I’m sure that they wouldn’t have predicted I’d still be here doing half of the things I’ve achieved since.
"Without Kelsey, I genuinely don’t think I would have made it through."
