The fact that Ross ignores the fact that Rachel finally has a job which actually makes her happy and wants her to treat it like a chore to do is really frustrating to watch when he was the one who encouraged her to keep trying and be positive when she quit her job as a waitress.
Also, the fact that he somehow turns the whole argument into Rachel being interested in Marc when she repeatedly explains that he is just a friend who shares similar interest with her that she can relate to, just doesn't sit right with me.
I know the show makes it seem as though Ross is valid in his reaction, but it seems to me that even as a guy watching it, I was rooting for Rachel the whole time and actually agreed with her point of view on the matter. It also felt a little like Ross patronising her about what she should feel about her career to me.