Infatuation/butterflies =/= being in love.
Infatuation is all about me. Omigod, he's really into me, he thinks I'm pretty, is he thinking about me right now, is he looking at me with stars in his eyes to match the stars in mine, I want his attention, I need his focus on me, me, me, gotta refresh my email, okay check it again, oh WHY hasn't he texted me yet, isn't he thinking about me me me???? He is!!! He's looking at me! He wants me me me!!!
That's an exciting experience, but also awfully stressful. It's not a place I want to be long.
Being in love is, for me, about having an intimately emotional bond with someone, to the point where it feels like family. It's not about me. It's about developing a loyalty, a devotion, a focus on another person. It's a rare sort of bond for me, but when I get there, then (barring extraordinary circumstances), that person is family to me, even if the romantic relationship ends.
There's all kinds of love and affection that exists even when there's no infatuation, and no "being in love," or in combination with these. Language fails to really encompass the bonds and attachments that we're capable of. Relationships don't have match up with cultural preconceptions.