There may be a connection. Many times we have people enter our lives because there is something we need to learn or experience. Such as, a kindred spirit. That does not necessarily mean they are to be in your life forever. One thing about negative relationships is the fact that we keep making the same choices over and over again expecting a different result. I am not saying this would be an unhealthy relationship, but you are having your doubts.
People gravitate to us for what we can give them. What they sense from us. Sometimes we are simply too close to a situation to judge correctly. So, don't kick yourself too much for not sensing something. You actually may need to learn something from having her in your life.
Okay, having said the above, you have thoughts which are not exactly your thoughts. Listen to your inner voice. I believe it is telling you what you need to know.
I would like to give you a more definitive answer, but these are your choices. If you are an empath, then congratulations.
Embrace your Empathness!