Their romance reads like a real-life fairytale - from their fateful meeting at university to their incredible wedding on April 29, 2011, and of course their three gorgeous children.
Despite the pressure of her royal role, Duchess Catherine has always managed to put being a devoted wife and mother first.
As Kate turns 37, we look back at her deep love for the most important person in her life - her husband, Prince William.
On their engagement
"We had a little private time away together with some friends and I just decided that it was the right time really. We had been talking about marriage for a while so it wasn't a massively big surprise. I took her up somewhere nice in Kenya and I proposed," William said.
"It was very romantic. There's a true romantic in there," Kate added.
On their extravagant wedding at Westminster Abbey in London
"It was supposed to be a small family affair," Prince William joked to father-in-law Michael Middleton as he gave his daughter away.
On Catherine's sense of humour
"She's got a really naughty sense of humour, which kind of helps me because I've got a really dry sense of humour," the Duke of Cambridge pointed out.
Want more on Wills and Kate's epic love story? Relive the best moments from their 2011 wedding day right here!
On raising their children and the struggles of parenthood
"Catherine and I are clear that we want both George and Charlotte to grow up feeling able to talk about their emotions and feelings," the Prince once told CALMzine.
"It is lonely at times. You do feel quite isolated. But actually so many other mothers are going through exactly what you're going through. But it's being brave enough, like you obviously were, to reach out," Catherine said of the challenges of motherhood.
On their festival wish-list
"I've talked about going to Glastonbury before because I do love my music and Catherine as well. I've got into enough trouble with my dancing recently. So it's probably best to stay away from that one," William joked on Radio 1.
WATCH: William and Catherine's engagement interview. Post continues after the video!
On how they unwind together
Although they don't watch The Crown, the couple love bingeing on box sets like Game Of Thrones and Homeland "once the kiddies are in bed."
They also love ordering in. "It's a real conundrum when it comes to it – pizza, curry or Chinese," William quipped to Catherine during their Radio 1 chat. "You do struggle for choice," Kate teased back. "I'm not so good with the spicy food," the Duke explained.
On their first encounter
"We obviously met at university - at St Andrews we were friends for over a year first and it just sort of blossomed from then on. We just spent more time with each other had a good giggle, had lots of fun and realised we shared the same interests and just had a really good time," Wills reflected.
"Well I actually think I went bright red when I met you and sort of scuttled off, feeling very shy about meeting you. Actually William wasn't there for quite a bit of the time initially, he wasn't there for Freshers Week, so it did take a bit of time for us to get to know each other but we did become very close friends from quite early on," Kate remembered.
On their famous break-up in 2007
"I think at the time I wasn't very happy about it, but actually it made me a stronger person, you find out things about yourself that maybe you hadn't realised, I think you can get quite consumed by a relationship when you are younger and I really valued that time for me as well although I didn't think it at the time," the mother-of-two has confessed.
"We were both very young, it was at university, we were both finding ourselves as such and being different characters and stuff, it was very much trying to find our own way and we were growing up, it was a bit of space and a bit of things like that and it worked out for the better," the future King of England explained.
On why they work
"When I first met Kate I knew there was something very special about her. I knew there was possibly something that I wanted to explore there. But we ended up being friends for a while and that was a good foundation," Wills has gushed.
"I think if you do go out with someone for quite a long time you do get to know each other very, very well, you go through the good times, you go through the bad times. Both personally and within a relationship as well. I think if you can come out of that stronger and learn things about yourself," Kate pointed out.