The singer, who is notoriously private about her personal life, has been dating Alwyn for four years.

Alwyn and Swift co-wrote some of the songs on the musician’s two latest albums, Folklore and Evermore, with the actor writing under the pseudonym William Bowery.

Now, speaking to Zane Lowe on his Apple Music show, Swift said that she and Alwyn initially bonded over a love of music.

"Joe and I really love sad songs," she said before going on to explain what it was like to write songs with him. 

"We've always bonded over music. So it was... We write the saddest songs. We just really love sad songs. What can I say?"

Swift went on to say that she was surprised when she and Alwyn started working together. 

"I say it was a surprise that we started writing together, but in a way, it wasn't because we have always bonded over music and had the same musical tastes.

"And he's always the person who's showing me songs by artists and then they become my favourite songs or whatever."

Swift seldom references her personal life in interviews. However, in 2019, she responded to a “sexist” question from an interviewer, who asked her whether or not she would be having kids soon given that she was approaching her 30th birthday at the time.

During an appearance on German news agency Deutsche Press-Agentur, the singer was asked if the birthday would be a “turning point” and if she would like to be a mother “one day”.

Swift refused to answer the question, which she suggested had only been asked of her because she is a woman.

"I really don't think that men would be asked this question when they turn 30,” she replied.