Diddy and Cassie on Video in Loved-Up 2018 Performance, Months Before Split

Cassie was pushing through with Diddy during their tough years together ... partying it up and getting all lovey-dovey on stage in Dubai -- before they officially called it quits.

TMZ has obtained this clip of Cassie cozying up to Diddy during his first-ever Dubai performance in April 2018 ... and you can see the two were all smiles as the rapper performed "I Need a Girl (Part 2)" at the opening night of the now-closed Gotha Nightclub.

On the surface, the pair looked happy, with Cassie glowing as she busted out some moves and vibed with Diddy. She got up close to share a hug with him before making her way to the edge of the stage.

You can also spot his sons, Christian and Justin, joining the fun in the video ... we're told Diddy even invited Christian onstage so he could belt out his new track at the time, "Love You Better," which he put out with Chris Brown.

A few months later, in October, Cassie's rep confirmed she and Diddy had broken up -- and had been for months. So, it seems their split happened not long after this serenade.

Of course, now we know their relationship had been tumultuous -- something made painfully clear by the 2016 hotel surveillance footage of the disgraced rapper beating her, which surfaced this year.

While Cassie now enjoys her freedom from the relationship, Diddy’s facing a much darker reality -- sitting behind bars with a slew of allegations hanging over him as he awaits his next court date on October 9.