Los Angeles, California - Ariana Grande and Ethan Slater are still fueling split rumors as insiders weigh in on their allegedly toxic romance!

The Daily Mail reports that not only have Ariana and Ethan been "on and off" for a year, they could also be headed towards a more permanent split!

Just to recap, the Break Up With Your Girlfriend hitmaker and her Wicked costar kickstarted their whirlwind relationship amid messy marital splits from their respective exes, Dalton Gomez and Lily Jay.

Now an inside source tattles that Ethan's notable absence at the MTV VMA's was because of an "argument just days before," although he and Ariana reportedly "made up soon after."

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They explained that the couple have "both been running hot and cold with each other."

As for the Wicked: For Good stars' future, the tipster said, "What they have going is more than a little toxic, but they're keeping it together for now."

Even the couple's alleged wedding plans are no longer "on the table," the insider dished.

"They fell head over heels in love when they first hooked up. But those days are over," they added.