Can we agree on some distinctions? I would suggest a threefold schematization: 1) Passion consumes. In that sense it would seem to be related to addictions. The relation of consumption being reflexive, you are consumed by what you consume... "Being passionately in love with someone" usually comes very close to denying the separate existence of the other, while indulging in self-destructive behaviours. Ditto for, caring for one's work passionately.
2) Being in love, though obivously bears within itself tinges of passion, is nevertheless distinct from it I would maintain. One can be in love with a person, a work, an object without necessarily wanting to consume it. But there probably is an element of possesives in "being in love" which distinguishes it from the third category I would posit, namely,
3) Loving, which is the tamest of them all... I am not using the term to depreciate the state, just to describe the quality of peace, which might at times though border on indifference.