Taylor Swift mentions singer Charlie Puth on 'The Tortured Poets Department,' and it's one of the album's biggest mysteries

Taylor Swift mentions Charlie Puth on "The Tortured Poets Department," prompting a welter of speculation.

• Taylor Swift namedrops singer Charlie Puth on her new album, "The Tortured Poets Department."
• She mentions Puth on the album's title track. 
• Fans are confused since Puth allegedly had a fling with Swift's friend, Selena Gomez.

Taylor Swift namedropped singer Charlie Puth in her new album "The Tortured Poets Department" — and fans are confused.

It came in the title track of the album, which dropped on Friday and included the line: "We declared Charlie Puth should be a bigger artist."

This led to plenty of speculation: why did she decide to name Puth, who she hasn't worked with, and isn't one of her well-known celebrity friends?

(Google Trends data showed searches for Puth's name spiking on Friday morning.)

Swift is renowned for packing her albums with Easter eggs and teasing references — it's part of what drives the intense fandom that drives her success and made her a billionaire.

Puth is one of the more baffling references, though.

The namedrop began to spread before the album's official release since it leaked early on Thursday.

Some viral social-media questions whether the leak was real, suggesting the Puth reference made so little sense that it could point to the leak being an AI-generated fake. But it was real.

A possible connection could be Puth's love life.

In 2018, Puth confirmed to Billboard that he had a fling with Selena Gomez: "Very short-lived, very small, but very impactful. And it really messed me up."

He said the romance inspired a song, "We Don't Talk Anymore," that the two sang together.

Another of his songs, "Attention," seems to line up with his romance with Gomez (although he hasn't confirmed that it's about her).

The song prompted some backlash after he explained in a video for the lyrics website Genius that it was about a former girlfriend turning down his sexual advances.

"We would be talking in the hotel, she'd be like, 'You wanna sleep over?' I'd be like, 'Yes, I'm gonna get it in!' And then nothing would happen, which is totally fine," Puth said.

"But after like the fifth time of that happening, I knew what she was doing."

Swift and Gomez are known to be friends: they were seen gossiping together at the Golden Globes in January, and everyone was trying to figure out who they were talking about.

So why would Swift mention her friend's ex on "The Tortured Poets Department"?

Fans also debated whether the line could relate to Swift's relationship with Matty Healy, the singer of The 1975.

A tweet from a fan account for The 1975 unearthed a screenshot of Healy praising Puth's 2018 collaboration with Boyz II Men, "If You leave Me Now."

So, it's possible that when Healy and Swift were together, they talked about Puth, which is why he gets a mention on "The Tortured Poets Department."

Puth hasn't said anything yet about the mention. And, without any more information, the debate is likely to continue.

Puth's representatives did not immediately respond to Business Insider's request for comment.