Once you meet your soulmate you can feel each other's physical pain above a certain threshold. Which means that while Meredith is oblivious, Addison is well aware who her soulmate is. But Meredith was happy. Who was she to take that away? (Somewhat based off of GA 12x9, with light mentions of 2x17, 3x4&16, 6x23-24, 8x...
What could have happened if Derek decided to choose no one, not Mer, not Addison? How could have things turned out? Meredith has no idea what's Addison truly like..
What would have happened if instead of Derek chasing Meredith into that exam room the night of the prom, Addison was the one chasing after her...