Recent reports suggested the Friends actors had got together IRL, years after playing a couple in the US comedy.
The British US Open champ joined the likes of Kim Kardashian West, Jennifer Lopez and Billie Eilish on the red carpet
The stars' This Morning interview also saw Jennifer mistakenly think she was asked if she was a hooker by presenter Josie Gibson.
Over the weekend, reports claimed that Katie had called time on the couple's engagement after five months.
The Irish UFC star appeared to throw a punch at the US rapper on the red carpet at Sunday’s bash.
The singer's huge diamond sparkler features a very special engraving.