I agree with everyone else that minus any real objective, agreed upon definition of the term Love, it's tricky even getting into these types of discussions.
For me - my personal definition of love seems to have always been a recognition that my concern for someone else's happiness and well being equal or surpass my own.
Because this understanding has a tendency to define what action will take place in a given circumstance. When this level of caring exists (love?) it seems to always carry with it a certain amount of self sacrifice.
Idealist - you raised the question around the common term "in love" which we hear so often, which is intriguing. My gut tells me that if we could interview enough people we would discover that what's truly being referred to is that infatuation (NRE) phase we go through when we newly connect with other people. The time in this phase seems to vary but generally it does pass. I've heard so many people make statements like "I 'love' my partner but I'm not 'in love' with them" where the perceived intention (or feeling) is that there's something now 'missing'. And off they propose to go in search of the Missing Chord. Like some "high" - some addiction. And all too often it seems that this search (and maybe even find) leads to much of the same crash and undesirable consequences as any addiction.