LIZ JONES: I don't blame cynics for not buying Harry Styles and Zoe Kravitz as a couple. She's landed a man millions lust over, yet she always looks so inexplicably, relentlessly miserable... I know what's really going on

Ever since Zoe Kravitz stepped out in New York with a ten-carat diamond engagement ring in April, after only eight months of dating Harry Styles, their relationship has been shrouded in scepticism.