Who even knew these two were dating?
Oh that's right because they've been together for less than a month!
We're guessing McCartney's camp couldn't stand Pain-In-The-Ass either because they're absolutely thrilled Hayden's been kicked to the curb.
According to a source close to Jesse "Katie is on a strict schedule with Melrose Place and Jesse's people really want him to stay out of clubs and live more of an adult lifestyle. They think Katie will keep him on track."
But Katie's people are quick to deny that the two love birds, who dated from 2004-2007, are back together saying: "Katie and Jesse are the greatest of friends, but there is no truth to them being back together romantically."
That doesn't mean they aren't back together physically.
[Image via Adriana M. Barraza/WENN.]