Cora and Mr. Bricker's relationship reached its peak. Maybe the Crawleys should lock their doors. Although in early 20th century England that probably would have implied scandal taking place rather than concern for one's safety.
I can't say I expected Mr. Bricker to go so far as to sneak into Cora's room, but it was clear that something was going to happen when Robert announced he was going to be out for the night. I was on the edge of my seat during the fight scene. Was it necessary to hide the whole thing from Edith? What I am not shocked about is Robert giving Cora the cold shoulder. I suspect he holds it against her that he turned out to be right about Bricker and that Cora kept inviting him over. It is very in character for Robert. Cora was walking a fine line the entire time, and I find hard to believe she didn't know otherwise. Cora knew Mr. Bricker was flirting with her and she kept ignoring it like it would go away. Mr. Bricker was clear about how passionately he felt about Cora, making it obvious that it wasn't just a crush. Did she expect it to keep going on without being addressed? It is easy to sympathize with Cora though; she and Mr. Bricker had a strong connection and talked about things she could never talk about with Robert. The second "break-up" was between Tom and Miss Bunting. Miss Bunting is like Tom before he was one of the family. She doesn't have the same experiences that have allowed Tom's perspective to change. She mentioned that she wishes they had met before he knew the Crawleys, but how can she be sure she would have loved Tom the same? It seems to me she fell in love with who he is now.
Once again my favorite scenes were those between Isobel an Violet. In Downton Abbey Season 1, these two were middle class and upper class polar opposites, but somehow that has blossomed into a dynamic, funny and genuine friendship. I think Violet is indeed resentful that Isobel's status will change if she marries Lord Merton, but I think her love for her friend trumped that resentment.