"They are happy and going strong," a source close to the couple tells PEOPLE

The latest Taylor Swift rumor has Calvin Harris on her list of ex-lovers, but a source close to the couple tells PEOPLE the split speculation is “absolutely not true.”

Adds the source: “They are happy and going strong.”

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Swift, 25, and Harris, 31, have remained mum about the reports – until now. On Monday, Harris tweeted, “It’s not going to be a ‘happy ending’ for everyone I sue for defamation of character for all these bulls— stories bye bye.”

Swift showed her support by favoriting the tweet. Meanwhile, further evidence suggests their relationship status has not changed.

Harris’ Social Media Activity

On Wednesday, Harris favorited a fan’s tweet about his girlfriend’s sexy covers of GQ and NME magazines. “When @CalvinHarris is a lucky dude,” the Twitter user wrote.

Harris (né Adam Wiles) favorited Swift’s tweet about the cover the next day.

Selena Gomez’s Latest Interview

If Swift and Harris were to have called it quits since then, her pal Selena Gomez, 23, would be among the people in the know. However, Gomez was surprised to hear about the reports on Monday morning. Fresh from performing songs from her new album Revival on Today, the singer fielded a question about the split chatter during an interview on Andy Cohen‘s SiriusXM radio show.

“Calvin Harris. Broken up or not?” Cohen asked.

“What?” Gomez replied, clearly shocked by the question.

“Are they broken up?” the host said.

“Oh, I don’t know,” she answered. “I think I would have found that out. Is that a rumor?”

Cohen pointed out that it’s a “major rumor” online, prompting Gomez to shut it down.

“Oh gosh, of course,” she said. “But weren’t they like … oh gosh, this is honestly, it’s so stupid. I’m pregnant every week. She’s going to be pregnant. It’s so stupid. Like, you can’t really read that stuff.”

Denial from Swift’s Rep

Tree Paine, Swift’s publicist, took to Twitter on Monday to indirectly address the reports, writing that others should “not believe the rumors.

Excitement over Swift and Harris’ relationship amped up after the duo were spotted holding hands on a cute date night in April. They took their romance to the next level in May, kissing and hugging during her winning night at the Billboard Music Awards.

“It’s going absolutely fantastic,” Harris said of the relationship in a July interview with KISS FM U.K..

Even back then, Harris accepted that speculation about their relationship was inevitable.

“For me, it could be a lot worse and I’d still be insanely happy with her,” he said. “It’s interesting because obviously there’s different things written about it every day and even if we don’t do anything publicly for a while, someone will make something up.”