Hi Kazine,
Just a few thoughts on this... The thing about love or emotional bonding is that the feelings you had towards someone are always going to be there at least a little. If you dated and loved your ex then you probably still do on some level love your ex. The reason this is confusing is you feel like in order to be loyal with your current partner you should have no feelings towards your past partner(s). The key to dealing with this is to recognize that it is okay to still have some feelings towards your old partner, that does not mean you are going to act on those feelings, or that you are not being loyal to your current partner.
Every event you have experienced in your life is somewhere still in your mind. Even if you can't consciously recall them. Your dreaming self was probably just remembering past feelings as if they were the present. Does that make any sense?
A resurfacing of previous thoughts or reactions is referred to in psychology as spontaneous recovery. Here is a good example from wikipedia:
For example, cocaine addicts who are thought to be "cured" can experience an irresistible impulse to use the drug again if they are subsequently confronted by a stimulus with strong connections to the drug, such as a white powder.
All the separate parts of you are still part of a whole. The reason it is so confusing is b/c it is possible to have completely opposite feelings at the same time. I love my ex and at the same time I hate my ex.