In the series finale, Rachel decided to get off the plane that would take her to Paris and her dream job so that she could live happily ever after with Ross, but this didn't make any sense. Ross and Rachel had been part of the central romantic, will-they-won't-they plot over all of 10 seasons, and the show's final episode was meant to bring them together definitively. However, the way this was done left several unanswered questions and entirely demolished Rachel's series-long character arc.
season 10 saw Rachel all set to move away to France for a massive development in her career. Ross always had difficulty getting behind her career choices, and job offer in Paris wasn't any different. He was terrified of losing her, so in a last-ditch effort, he chased her down at the airport, told her he loved her, and begged her to stay. Of course, he didn't get his answer right then and there, but later (after some healthy anticipation building), Rachel appeared at the apartment and announced that she had gotten off the plane—just for him.
Rachel's dramatic appearance at Ross' apartment was the grand romantic gesture to end the series, but it couldn't have been that easy. She had planned an entire move to a different country, not just for her but for her daughter as well. This wouldn't have been an easy task and would have been just as difficult to back out of. , Rachel didn't just give up a move, she gave up a job. So, by leaving the plane, she might have gained a boyfriend, but she lost a lot more. provided no explanation for what Rachel's plan would be going forward—other than just being with Ross.
This is made even worse by the fact that when Ross first found out that Rachel had accepted a job in Paris, he had several interactions with Rachel's old boss at Ralph Lauren that all but guaranteed that she wouldn't be hired there again. Of course, Rachel didn't know about this. So, by getting off the plane, . In comparison to love, this might seem like an acceptable trade-off. However, in the case of Rachel, it spoiled her entire arc.
Over the 10 seasons of , Rachel grew from being a spoiled girl who didn't even know how to get "one of those job things" to a professional in fashion. She proved that she not only had what it took to survive without her dad's success but the intelligence and passion to create that kind of success for herself. This is something that Ross struggled to get on board with, and his frustration with her changing career contributed to their . Still, despite having her heart broken, Rachel rose even further in her achievements.
Therefore, when Rachel gave up her career for a man who had never supported it to begin with, she threw her series-long development right out the window. This also meant that Ross' arc remained stagnant since getting in the way of her job only proved that he had never learned from his mistakes. Ultimately, it should have been Ross who made the sacrifice. Perhaps, he could have instead shown up in France to announce that he would always be there for her (pun intended). Ultimately, many alternatives would suffice, but Rachel's giving up everything wasn't the ending she deserved.