The first "hit" I get from reading your post is that you are just not happy. Whether poly or mono, if you were feeling more positive and joyful about your life, you would be exuberantly and excitedly engaged in your relationships, and wanting to be with your partner(s). But your post paints a picture of someone who is very dissatisfied (with your home life and marriage, but maybe even just life in general?). I felt sadness come over me as I read it. So, perhaps it is time for you to look at creating more satisfaction in your life and finding ways to be happy, regardless of whom you diddle.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein