My opinion, for whatever it's worth, is that Adam KNEW that Rachel was the right one, but he was afraid of commitment, and he was so pressured by his family that he opted out... and chose the safe one... one that he could have a casual relationship with, and one that he can safely breakup with without offending his family. He knew he was not ready, he stated that he would have to mature before he was ready for a relationship like that. Perhaps he did Rachel a big favor....