Owen Hunt found himself facing the difficulty of sorting out whether or not he was ready to move on into the next phase of his life, and where his often complicated bond with Cristina Yang might fit into that life. We found out early in the episode that Emma Marling, a Seattle Presbyterian physician he'd recently met, had broken things off with Owen upon learning he hadn't told her he'd been married to Cristina. Owen's awkward discomfort at the whole situation was evident as Callie Torres and April Kepner tried to encourage him. After Owen walked away they both agreed with Emma's assessment that he wasn't yet ready to date.
In contrast to his earlier discomfort at the discussion of his personal life, we saw the relative ease with which Owen and Cristina interacted when a truly unique cardiac case presented itself in the emergency room. The patient possessed situs inversus, a congenital condition in which the major organs were reversed from their normal position. The delight with which Owen presented Cristina with this 'treat' on Halloween was clear from the broad smile on his face when he assured her he knew she would be keenly interested in this particular surgical case. Watching Owen and Cristina interact so surely with each other in the operating room was a bittersweet reminder of both the remaining strength and yet the current fragility of their connection.
As the surgery continued to focus them both professionally it was soon clear they were communicating somewhat at cross purposes, a further mirror to the communication quandry in which they've found themselves since the season began. While Owen repeatedly brought up his frustration with the complications of operating on a patient in which the organs were on opposite sides of the body, Cristina reminded him in return to focus and trust his experience and abilities to get him and their patient through. Owen, in turn, advised Cristina to just go to the Halloween party to which Meredith Grey had invited her rather than overcomplicate her reaction.
While I do think fans were right to see Owen and Cristina's remaining ability to connect and communicate as a good sign in these scenes, we later saw how their interactions have poised them for potentially separate paths, hopefully only temporarily, in which they both must find their way to their own answers to where they fit in life. Owen took further action on Cristina's advice when he successfully reinitiated contact with Emma, saying he hadn't told her about Cristina because things had always been complicated between them. Meanwhile, Cristina arrived at Meredith's party, requested cupcakes in tow, only to find herself feeling distinctly out of her element whereupon she retreated before being seen by anyone, leaving the cupcakes behind as evidence for Meredith to find of her friend's surprising actions.
Elsewhere in the hospital: Richard Webber continued to heal and teach as best as he can from a hospital bed; Miranda Bailey faced the unexpected surprise of her husband Ben's appearance and the news that he'd quit his hospital program in California; Derek Shepherd continued to balance brain mapping research with family life; Arizona Robbins stepped further into her new relationship with Leah Murphy who had been attacked by a patient; Jackson Avery spent the day shuttling between tending his girlfriend Stephanie who'd recently had eye surgery and working with April, his friend and former girlfriend; Shane further struggled with his guilt over his role in the death of his colleague Heather Brooks; Callie continued to try to move forward vicariously through the lives of her friends while also calling a short cease fire with her wife Arizona so that they could both enjoy Halloween with their daughter Sofia; and Meredith continued to struggle to balance family, work, and her friendship with Cristina.