Sirius definitely related to that feeling. They had come together, albeit from much different times, yet he felt like he hadn't seen him or really spoken to him much. Especially recently. And whenever they did talk, the conversation always seemed to be, or become, a downer.
There was a pause before Sirius asked, "Why?" He'd already given his reasons and he wasn't sure what exactly Remus disagreed with. The thought of him quietly bothered for all this time without saying a word made him feel especially bad.