Taylor Swift 'has An Ex Rulebook'

Taylor Swift has reportedly created an ''ex rulebook''.

The 'Bad Blood' hitmaker, who's dated a string of stars, including John Mayer, Harry Styles and now Calvin Harris, uses her rulebook to offer relationship advice to her friends, including Oscar-winning actress Jennifer Lawrence, who's currently dating Gwyneth Paltrow's estranged husband Chris Martin.

A source told Grazia magazine: ''Taylor has drawn up an 'ex rulebook' as a go-to reference for her friends who have recently split up with someone. She's also very good at advising her girl group on how to get more commitment from a man.

''She's telling Jen how to deal with her relationship with Chris, especially because he spends so much time with Gwyneth.''

What's more, it's been claimed the 25-year-old star - who also counts the likes of Lorde, Gigi Hadid and Emma Stone among her close friends - has become a trained love coach who is able to offer good advice to her pals.

The source added: ''Taylor is very good at offering advice. She's secretly trained to be a love coach and was doing a course online. She qualified last month.''