The '22' singer approached the British actor in at a party in Hollywood last November, but he initially rebuffed her advances.
A source told the New York Daily News newspaper: ''Taylor kept on making an effort to flirt with Douglas, but he gave her the cold shoulder and was extremely dismissive towards her.
''She would get a drink and then approach him; she would chat with [actress] Hailee Steinfeld and then re-approach him; she was even trying to chat him up near the flowers on display. It was all very funny for those of us watching.''
Taylor - famous for writing songs about her exes, who include John Mayer, Taylor Lautner, Harry Styles and Jake Gyllenhaal - even complained to Hailee - who starred alongside Douglas, 21, in the 2013 version of 'Romeo and Juliet' - that the actor wasn't responding to her flirting.
The source added: ''Taylor and Hailee were chatting about Douglas while they all touched up their makeup. Taylor was whining and complaining about his aloofness toward her. She looked like an animal circling its prey, when she tried to get his attention.''
However, Taylor's persistence eventually paid off and she went on a couple of dates with Douglas in London, but he has now ruled out any chance of romance completely.
One of Doug's friends confirmed: ''Doug is a young guy and is enjoying the single life. He was quite taken aback about how keen Taylor was. She has been in touch with him, but he just wants to be friends.''
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