For some reason, I remembered The Tomorrow People yesterday -and one of my most favorite pairing ever: John/Astrid. I loved them, I loved them so much, the relationship based on understanding and trust that they'd built over the season...
Also, this was one of the best "eff you" to your ex that I've ever seen, when John asked Cara to bring Astrid down into the bunker to keep her safe. I loved it mainly because John did NOT do it to rub Cara's nose in the fact that he didn't need her anymore, he honestly only thought about Astrid's safety.
But Cara's look and realization that, after she had found him lacking and dumped him for her Stephen, John found someone else and he and Astrid had build something solid between them without her or Stephen actually realizing it.
That was... wow. YEARS later and I'm still smitten!