My guess: She simply couldn't decide between Edolas and Earthland Fairy Tails. We didn't see two Lisannas, after all. From a coldly psychological pov, Earthland buried their Lisanna (as far as they know) a long time ago and have thus dealt with the pain already, while Edolas Fairy Tail was happily living with Lisanna. Staying in Edolas would have been the way of least pain for others.

However, we won't give a damn about Edolas anymore, so it's better this way: She never got a chance to make the decision herself, getting sucked back by the reverse anima just like the rest of Earthland suckers.