The singer, who found fame as part of the band Stereo Kicks on the ITV talent show in 2014, has paid tribute to Dani in a heartbreaking post on Instagram, in which he said she had died before they could be married.
“I can’t believe I am writing these words but my darling Dani – my best friend, my everything and more, the love of my life – passed away in the early hours of Saturday morning,” Tom said.
“What was supposed to be the happiest day of our lives ended in irreversible heartbreak. I feel like I have cried an ocean.
“We never made it to the altar; or got to say our vows, or dance our first dance, but I know you know that you were my entire world and the best thing that has ever happened to me, Danielle. I will wear this ring that I was always supposed to wear as a sign of my unconditional love to you.”
Tom also vowed that their eight-month-old son Bowie would grow up to “know how amazing his mummy was”.
He continued: “I am completely broken trying to process this and I honestly don’t know where to go from here, but I do know I need to use any strength I can muster for our little boy.
“I will not be a mark on the parent that you had already become but I promise I will do my everything to raise Bowie just the way we always wanted. I promise you he will know how amazing his mummy was. I promise to make you so so proud.
“My darling Dani, the brightest light in any room, my world is nothing but darkness without you. I will miss you forever.”
The cause of 34-year-old Dani’s death has not been revealed.
Tom and Dani, who worked as a PR executive, became engaged in December 2019, and had already postponed their wedding during the pandemic.
Lewis was among those who offered their condolences, commenting on Tom’s post: “Love you brother.”
Ellie Goulding wrote: “I’m thinking of you non-stop… You are so strong. Here for you always.”
Girls Aloud’s Nadine Coyle also commented: “Sending so much love, light & healing to you, Bowie & everyone who loved Dani!!”