Demi Lovato has failed to rule out whether her song 'Ruin the Friendship' is about Nick Jonas or not.

The 25-year-old singer previously sparked speculation she had feelings for her pal because the album track features lyrics about her wanting more from a companionship, and while the star hasn't denied such claims, she will never reveal who her tunes are written about.

When asked if the track is about Nick during an appearance on 'The Ellen Degeneres Show', she replied: ''Something that I will always keep to myself is who I write my songs about.''

Demi burst out laughing while answering the question, prompting talk show host Ellen to presume the song is in fact about Nick.

She said: ''I see, so it's probably about him ... you're best friends?''

Demi continued to laugh and started blushing before admitting the pair are good pals, but didn't confirm nor deny whether the song in question is about him.

She deflected such attention later on in the interview by joking she secretly has feelings for Ellen.

She said: ''Ellen, I want to ruin the friendship with you. It means I'm secretly in love with you.''

Another of Demi's new tracks 'Only Forever', which also features on her latest album, 'Tell Me You Love Me', is also about wanting more from a friendship, and the 'Sorry Not Sorry' hitmaker previously revealed she sent the songs to the person in question.

She said: ''I was frustrated with a certain situation.

''And I was like, 'You know what, I'm just going to write about it.' And so I did, and sent [the songs] to that person, and that was ... Interesting.

''Any time you send a song about the person, to the person - it's ballsy. It's like, 'Hey! Here's my feelings for you!' ''