Clara Alvarado plays the character of Ariadna in Money Heist. Ariadna was working in Mint and one of the hostages in Royal Mint.
In fact, Berlin was in love with Ariadna. But she was doing romance with him just to keep herself safe from the robbers. Berlin has revealed that he has only one to two years left to live because he was suffering from incurable neurological disorder.
He did romance with her and assure her that they went for a world tour after robbery. All the money with Berlin would be of her after Berlin death.
It was evident in second season 7th episode that, Ariadna was not in love with him and she was pretending to be in love. In last episode of second season, Berlin was killed by cop while helping other robbers to escape from the Royal Mint.