Sources connected to the former couple with direct knowledge tell TMZ, when Ariana and Dalton hooked up in 2020, they were everything to each other -- company, romance, support ... all of it.

When Covid restrictions lifted, we're told their differences became alarmingly apparent. Dalton, an L.A. realtor, was taken aback by Ariana's celebrity. He had not dealt with her schedule, the paparazzi and the various opportunities that took her out of L.A.

We're told Dalton would sometimes question why they needed to go around town with security, something that was a must for Ariana.

Their differences started to make the marriage unravel, and it was greatly exacerbated when she went to England last December to begin filming "Wicked."

By January, they were separated, but still on friendly terms. They began living separate lives until May, when they decided to take a shot at it again. That lasted 2 weeks before they both threw in the towel.

Fact is ... we're told Dalton has been dating over the last few months, which was fine with Ariana. Our sources say both Ariana and Dalton were "shocked" no one picked up on the separation until today, when TMZ broke the story they had gone their separate ways and were headed for divorce court.