S2 finale - How could TPTB do that???

I don't understand what the point of screwing Danny over was?

He was doing really well with his recovery and he was serious about being in homicide and adoption and he really really loved Jess and TPTB just screwed him over. WHY????

Seriously I just always act like the finale never happened. It doesn't make any sense at all.

Anybody got any thoughts on this?