Gigi Hadid & Joe Jonas: We're Breaking Up

It was a nice little run, but Gigi Hadid and Joe Jonas are done -- they're breaking up.

TMZ confirmed the couple formerly known as G.I. Joe decided to call it quits after what amounts to an extended summer fling. A source close to the couple tells us it was all about their schedules. Joe wanted to focus on his new group DNCE ... which is just kicking off a new tour.

And of course, Gigi is busy being one of the hottest models in the world.

They were last seen out on Oct. 25 in West Hollywood (not looking thrilled), and the fact they weren't together for Halloween, and Gigi was solo at Kendall Jenner's party ... shows the split's been in the works.

It's particularly bad timing for Joe, since he could've had a front row seat when Gigi walks the "Victoria's Secret Fashion Show" next week.