There's a pretty good analysis of love
here, both scientific and unscientific. Most people probably mistake a lot of things for love. The first phase of a relationship is *not* what love is. It only lasts for a few months maybe, and is mostly a reaction to hormones. When you truly love a person you know that they're not perfect, you know all their faults, but you don't care because it's part of who they are and you love them for who they are. I think that's the biggest part of it. But to get to that point, you have to know a person for a very long time. So it's not something like BAM! and you're in love. It happens slowly, sometimes over years.