John Foster took away all her painful memories, including the bittersweet ones. The memory of her first kiss with Freddie is so intense that it can’t be allowed to stay. This is why she talks about the pond when she re-introduces herself to Cook. Not only did she forget him, but the whole pond as well. The audience is left to pick up that both boys have caused her pain and therefore been erased. I’ve watched this episode three times, and I just now saw the connection. Such a cool reflection of where she is. I love the Skins’s writers.