Passion and Obsession

I've realized over the last year that there is a fine line between passion and obsession, and yet I still haven't found how to put into words the relationship between love and passion. Within the context of people, I think passion is everything that love is, but I've been wondering if you can have love without passion... It feels wrong to say you can have an impasssionate love, and while I usually go with my gut on things, I am tempted to say you can. Maybe an impassionate love is not that at all, but simply a love not yet grown in full. And I think you can't understand obsession without first understanding selfishness. The obsessed person obviously has nothing but their own selfish desires at heart and will almost always cause damage to both themselves and another. And while being passionate can definitely hurt at times, at least you're not hurting others.