I don't see the Rose Hardin instance as comparable with those others. It seemed to me that Rose was always supposed to end up with John from her inception. Hal was supposed to eventually get back together with Carol. He had an interest in Rose so the writer could use it as a catalyst for tension between Hal Jordan and John Stewart for the sake of drama.
It would make little narrative sense to have Rose on the Mosaic World where John was at, so that she could be Hal Jordan's girlfriend.