Parting isn't always so sweet? Brandi Glanville and boyfriend Calum Best butt heads in a heated debate during Famously Single's finale on Tuesday, August 2, as seen in Us Weekly's exclusive sneak peek.

The E! dating series' preview clip shows Glanville, 43, and Best, 35, hitting the bar together, where the British model orders five shots for himself.

"Calum was doing these shots, and I saw him change," the Real Housewives of Beverly Hills alum tells the camera. "It was a little scary."

After Glanville expresses concern about his drinking, Best unloads on her: "You f--king wreck my head though, man. You have to stop this s--t, you know. You don't show me a goddamn thing — if anything, you put me down because of your defense mechanisms or whatever they are."

"You tell me that you need me to make you sure you're No. 1, which I've done from the beginning, but then you crack on like you're not interested," he continues.

Glanville fires back with, "No, you don't make me feel like No. 1." At that, Best replies, "You shut me down — how the f--k does that make me look? Like a c--t. I'm not here to look like a c--t."

The pair initially clicked at the start of the season, but they have grown more and more distant as they've spent more time together.

Watch the tense clip in the video above. Famously Single's finale airs on E! Tuesday, August 2, at 10 p.m. ET. 

Want stories like these delivered straight to your inbox? Sign up now for the Us Weekly newsletter!