Ross and Rachel have a lot of ups and downs in their relationship and in the series, but here Ross absolutely kills their relationship. Rachel made it clear that he could come to her office, and he ignores her. Ross then makes things worse at her office, prompting Rachel to kick him out. Rachel's character development comes full circle here as she finally gets to be a professional, and Ross ruins it. The fact that is is their anniversary is a moot point (or a moo point). Ross then is completely unreasonable when Rachel comes home, saying it's just a job. He doesn't listen to her, he ignores her boundaries, he makes things worse. He absolutely deserved the breakup. And then he sleeps with the Xerox girl that same day. This is Ross at his lowest. Phoebe is pretty low in this episode as well.
All of that being said, they were definitely on a break.
All of that being said, they were definitely on a break.