And another celeb couple bites the dust! Kate Upton and 'Dancing With the Stars' professional Maksim Chmerkovskiy called it quits. What happened?

The pair were set up through mutual friends and very lovey-dovey, even as early as Upton's 21st birthday on June 10.

As recently as October, Chmerkovskiy was gushing about the busty model. "She's an amazing person," he cooed. "We have an incredible time together, and, you know, I definitely didn't see that coming and I think neither did she. We enjoy each other's company very much and like I said, she's a great girl that I never thought anything romantic like this could have happened."

And it turns out he still feels that way -- the relationship just didn't pan out that well.

"They are really good friends still and speak all the time, but their schedules just made it too difficult and it fell apart," a source told Us Weekly. "[Chmerkovskiy] has a lot of respect for her, but it just wasn't working anymore."

Bummer!