SMG and DB are not the first or the last actors playing an onscreen couple that played it up in real life for some buzz. It's done all the time.
No - but she never did that with JM, she never did that with her Ringer co-stars. Anyway - I don't care either way. All I care about is what translated on the screen. They were obviously comfortable enough with each other and I think that sells the fictional relationship. Thats really all I care about. 🙂