Your present-day relationship could end up mimicking your bond from a past life -- a bond that was erratic at best. Then, you may not have known how you felt about your partner, and if you did, you didn't (or couldn't) allow them to be secure in your feelings for them. Now, that same sense of instability will exist between you again, only this time it will actually impede your partner's personal, karmic growth.
Still, they may try to hold on to your relationship because being with you will feel forbidden and exciting, as if they're breaking the rules just by becoming intimate with you. It's even possible that your friends or family, or theirs, will oppose the relationship, giving things even more of a taboo feeling. But both of you should focus less on the excitement of unpredictability and more on what each of you actually needs from a romantic affair. Your partner's karmic evolution depends on certain things, among them a certain amount of stability and emotional openness, that they won't necessarily find with you. It may end up that the best thing either of you can do for the other is to move on and find someone who's a better match for you.