Lady Kitty Spencer and Michael Lewis first got together in 2018 after a mutual friend introduced them to each other. The Evening Standard reports that Lewis, a businessman, comes from a prominent South African family. He owns retail chains in his home country, the UK, and Australia. Spencer and the very wealthy Lewis reportedly got engaged at the end of 2019, but the couple is notoriously private. In May 2021 interview with Town & Country, Kitty told the publication why her relationships are off-limits with the press. She explained (via Yahoo Life UK), "I feel less vulnerable when I don't discuss things like my love life. I just think, 'Really, what's that got to do with anyone else?' It shouldn't make a difference to anyone's day."

Kitty went on to say, "It's because, for me, love is the most important thing in the world, and I will protect it with all my heart by not making it a topic of discussion. You open yourself up to other people having opinions, and it just isn't relevant to anybody's life but mine and my family's." Kitty and Lewis tied the knot in the summer of 2021. At the time of their nuptials, Kitty was 30, and Lewis was 62. The couple has a 32-year age gap, and Lewis is also older than Kitty's father, Charles Spencer. In 2021, the 9th Earl Spencer was 57 years old.