"Must Be Love" follows the love story of Taylor, better known as "Tay-Tay" played by (Taylor Swift) and her childhood best friend Harry (Harry Styles). But what will Tay-Tay do if she starts falling in love with her best friend?. And what if Harry only sees her as a 'best friend'? This problem will develop when another girl enters Harry's life. Unfortunately for Taylor, it's her cousin Ema. Will Harry fall in love with "Tay-Tay" or will they remain as best friends forever?