Had they given John/Astrid more build up, I could get on board with that particular pairing, but Stephen/Cara... Can't do it. What they should have done is put both couples on a slow burn throughout the season. Instead, they had Cara/Stephen bone within the first 6 episodes.
After that, there wasn't really much to do with them... Enter Hilary, who Stephen arguably had better chemistry with, and an over all better progression of a relationship. They were rivals, then partners, then lovers. All the while Hilary was lying to Stephen, because she thought she was doing what was best for him...
Cara on the other hand just seems to be there. Fighting with John. Barking orders at everyone. ****blocking Stephen. Falling for John all over again. If Stephen/Cara are supposed to be the OTP, the producers/writers haven't done a great job of making that clear.