I used to be a complete "love addict". This meant that I focused so entirely on the object of my "love" that I lost complete track of myself. It would get me into the mos horrible situations.
But when we get "addicted' to someone else its because we feel lacking in ourselves and only feel better when we are getting our 'fix" of the attentions of this other person.
Then, when you are not around this other person you feel the "withdrawal" symptoms of despair and pain. This is not the pain under your need to be filled up with this other person, this is the addictive focus on the other person which keeps you hooked into the drama so that you can avoid the real issues. Its really painful nonetheless.