I was doing some thinking regarding the adolescents that I work with and their ideas on love. (Also, the stories of a number of friends and their relationships come to mind.) Love, oxytocin (the attachment/cuddle chemical), adolescent hormones and their concrete/non-abstract brain functions, past traumas, predispositions to addiction and much more seems to affect whether a person starts using relationships as an addiction. Many addicts will use drugs, alcohol or relationships to numb painful feelings and get that good/wanted feeling, and they are forever chasing that initial high even when the relationship (with the substance or significant other) goes terribly wrong.
Here's an article that explains this concept:
Just something to think about.