He stares at her empty desk and it hits him, suddenly, sharply, that she's never again going to look up and tease him, never again going to laugh or smile. He glances at Gibbs' desk and wonders how he's feeling. Tony got over his own crush on Kate a long time ago; she was a friend, a sister to him. But Gibbs – there was always something more between them. Tony had seen it even on Air Force One.
Gibbs and Kate were supposed to realize they were in love, and get married and have children and live happily ever after. They deserved that; Kate deserved that.
There's no time for should-have-been's. They have a killer to catch.