You should take special care to be perfectly aboveboard and honest with your partner, because they stand a significant chance of being utterly misled through the course of this relationship. Most likely, it isn't due to any intentional deceit on your part, either; they just aren't able to see you clearly through those filmy, rose-colored glasses they're wearing! They idealize you from the beginning; they believe you have a lot in common, and they fantasize that you could be the one their soul has been seeking all along.
Maybe there is something really significant and special between you, waiting to be discovered. But there are also plenty of bad connections, like a phone with static. Even the best couples have flawed communication from time to time, and the best couples are able to view each other holistically, meaning, as the people that they really are -- warts and all. If you two can't do that for each other, you're bound to end up disillusioned when things turn out not to be what you expected. Part of the problem here lies in the fact that you've done it all before -- not in this lifetime, but in a past one, in which you were lovers. You either intentionally or accidentally misled this person as to your intentions for the relationship. Don't make the same mistake this time; try to be really clear and realistic with each other about what you're looking for, and what you have to offer.