I was liking this episode quite a bit, and even hoping we'd get past the Bones-ish sillyness of Castle and Beckett not just taking the relationship the next step like proper adults.
It has been fun to see them tiptoeing and denying/playing it out, but enough is enough. They've been almost but not quite saying it so many times, suspension of disbelief can only do so much. The writers expect us to believe they didn't just take 1 hour after work one day and got it said with no interruptions?
Please...get it done or move on. The whole teenagey back and forth is taking away focus from a lot of the other great things about the show, including Castle and Beckett working great as a team, with or without romantic feelings.
The last but not quite as severe reason why this for me went from a possible top episode to one slightly below average was how Castle just pieced the whole thing together in the end. That was a bit of a hail mary, they could have done better with that.