Someone at Radar Online saw with their very own peepers the demise of the long time relationship between young Hayden Panettierre and the old Milo Ventimiglia Wednesday night.

We’re seven hours late for work today because we partied at Crown Bar until we passed out – no, not from drinking, from shock. It happened right after we saw 19-year-old Hayden Panettierre ALL OVER Jesse McCartney. The Heroes star was sitting on Jesse’s lap while he kissed her neck. Then she got up and did some crazy sexy dance in his lap.

The insider also saw the two outside in the smoking area get close and cuddly.