However, these two relationships are not the only notable romances the Princess Royal has had. On watching this year's season of The Crown, season three, many were shocked to learn of one royal former couple.
Tina Brown wrote in 2007: "There was a romantic re-enactment of 'La Ronde' on the dance floor at Annabel's one night in 1971 when it was clear that Princess Anne was in love with Andrew Parker Bowles."
Regardless of any romance that once was between the pair, the two old friends seem to still be very fond of one another.
They are often seen side by side at racing events, cheering on horses and comparing notes.
What can their body language tell us about their friendship now?
Body language expert Judi James said: "While not exactly a 'BOGOF' deal, the Parker-Bowleses did provide an odd quartet-styled relationship for Charles and his sister Anne, with Anne once dating Andrew Parker-Bowles and Charles embarking on his now legendary relationship with Andrew's wife Camilla.