Friends: 10 Reasons Why Ross Is The Worst Person Ever
1. We Were On A Break
Now, before things get going, let's get one thing out in the open: Ross and Rachel WERE on a break - Ross is right about that. But it doesn't even remotely justify what he did in the one night they were separated, when he was still madly in love with her.
After taking a break - after the whole "it's just a job" fiasco - Ross goes out with Joey and Chandler and ends up in bed with another woman. The next morning, he receives a call from Rachel saying she wants to make up, so he tries to hide his indiscretion from her by making sure the news never reaches her.
This fails, and the two break up for real.
At the end of season three, Rachel gives him a long letter in which she says Ross needs to take full responsibility for what went wrong in their relationship, which he does without knowing what he's taking responsibility for. When he finds out, he keeps yelling "We were on a break!" and breaks up with Rachel yet again.
All told, it was completely his fault, and all he had to do was own up to the fact that he made a mistake. But, in his Ross-ness, he couldn't, and ruined their relationship almost beyond repair. What a fool.