I agree with everybodys sentiments on here @Alexy and @caroline, I will look into this Dopamine thing more as well. Might explain a few on my ups and downs when I see or speak to certain people.

Only thing I want to add to the mix is, have you thought about travelling again and getting some adventure back in your life?? Maybe thats what you actually crave rather than a human being. Also its very easy to do things over Skype etc but never back it up in real life.
I would move on, travel and enjoy life, its going to be tough.