Dreaming of exes

Why do I always dream about my ex boyfriends? I have been with my husband for 6 years and at least half the nights I am dreaming of an ex. And not only do I dream of my exes, I dream of my husbands exes. Last night in my dream his ex fiancé showed up at our house all upset over her own relationship. Mind you I have only see this woman in like one picture, but I could pick her out of a lineup and apparently dream about her!

Why is this happening?! I want to tell my husband but at the same time I don’t.