Rojas’ departure means that Upton will have lost a friend and roommate as well as coworker, and Rojas was arguably the closest person to Upton other than Halstead.
While I could see Upton living alone actually opening P.D. up to more Upstead, I’m already sad that Upton will lose one of the very few people she has opened herself up to and P.D. will lose a complex character.
Well, that backfired on Upton somewhat, when she crossed some lines to protect Rojas and got herself shipped off to the FBI (and FBI in the first NBC/CBS crossover of Dick Wolf shows), but the friendship was strong.