So if I remember correctly when Elijah compelled Kathrine to stay in the tomb with the rest of the desiccating vampires, she told Damon NOT to kill him or else she would be trapped in there forever and when Damon daggered him the compulsion broke
SO, Alaric was turned into a vampire by ester with the original vampire spell
NOW, when Alaric compelled Elena to forget she loved Damon, shouldn't she have remembered loving Damon after Alaric turned back into a human when jo saved him after he crossed the border ?