I like Cath, always did right from the beginning. And I didn't mind her becoming a series regular. Where it went wrong was when they decided to have her leave the Navy and then really not know what to do with her after that. That wasn't the actress's fault. I think it's a shame what happened and as a result she got caught in the middle to some extent.
I liked this episode too, but not because of Cath's exit at the end. But it was, in my opinion, one of the better episodes this season and I felt Michele Borth knocked it out of the park with her swan song as it were. The end was heart breaking on a lot of levels. Danny once again goes half way around the world to get Steve, then stands up to the military when they think they can just dismiss him. (They've clearly never dealt with Jersey snark, especially when it's protecting one of it's own.) It never ceases to amaze me what Danny will do when it comes to Steve-- Steve gets captured in N Korea- Danny (and the rest of the team) go and rescue him. Steve goes to Afghanistan and gets captured and there is Danny again. This was a man who up until he was forced to move to Hawaii, never left the Newark/NYC area except to go to the Jersey Shore. Steve- "Why are you here?" Danny with a shrug "I wanted to make sure you were okay." The two have been at odds most of the season, the chemistry off a great deal of the time- but it was there in that moment and it reminded me why I loved this pair so dearly.
But as Danny makes sure Steve understands that no matter what, he'll be there-- Steve has to let Cath go. Her decision is heart breaking but noble and understandable. She owes a debt and she will see it through. Through these past two seasons, Steve would never completely commit to her, admit out loud what she was in his life. It seemed she'd always been that much more invested in the relationship- people all around him pointing out that she was in love with him. Up until that moment though, when he realized he had to let her go, only then could he finally say what he wouldn't before. Maybe because it was safe to now, because she was half a world away and not coming back anytime soon, but Steve finally comes clean and then says goodbye.
Everybody in his life either leaves him or dies. Yet there is Danny, and by default, Gracie- who remain the one constant that doesn't change. For now.