My chemical levels are low....

I was reading this morning about the chemicals that are involved when we fall in love. I don't know why...
But it's something about PEA- phenylethylamine. It a natural amphetamine, gives us energy and makes us feel all those excited jittery feelings, the ones that happen in the beginning. The ones that will ultimately be the demise of your life if you do something stupid, like get move in together, get married, get pregnant or leave your current spouse before they wear off. Apparently after the PEA wears off, then your body creates dopamine, which stimulates the production of oxytocin. This is what keeps us around, it seems. The warm and cuddly chemicals. (granted I am reading this information off of some web sites so I'm certain that I'm missing important biochemical information, blah blah...
But anyway- my point is that chemicals seem to have alot to do with why we fall in love, and how we stay in love. This is an idea that I can grasp. I have issues with sociology and theories. Give me facts any day.
So in keeping with this whole chemical thing, I have a thought. Why is it that after a few days of not talking to someone you care about, you start to miss them. That weird aching in your gut, the weight that sits on your heart. I wish I had a big vocabulary to explain it better. Is that the result of your body not creating that domanine? A low level of the oxytocin that seems to pump through us constantly when we are in love? Because it seems to me, that as soon as the object of our desire returns- even with something as small as a phone call...we return to our "normal person"state, and no longer feel that emptiness. We have our fix and are high once again. We all have our addictions...