In a past life, you two were probably involved. It may have been romantic or it may not, but either way, it turned ugly -- and probably because you ended up dominating this person, squashing that passion and spirit that could have been so beneficial to you both. You may have been lovers with a warped power dynamic between you, or you might have been a warlord and a prisoner or any of a host of other relationships in which you wielded total power over them.
In this life, your relationship holds at least shadows of that old dynamic. Though you may have a passionate connection, you feel a tension when you're together that might be unexplainable, since it's there between you from the first time you meet. It's a result of that old, unhealthy bond that you had long ago in another realm, another lifetime. You may get the feeling that you've done it all before, and you're right. So why make that mistake again? This lifetime is giving each of you a chance to do things differently. Especially if other aspects between you point to passion, aggression and domination, it's really difficult to break out of those old patterns. You might find yourselves acting out an old relationship dynamic that you don't even remember, but that will be just as destructive and unhappy this time around.