Being "in love" is really more of a feeling. You get giddy, excited, or nervous when the other person is around. It's a pleasant feeling but it DOES fade over time. The more you get to know someone and spend time with them, the more flaws and rough patches will pop up.
That's where "love" comes into play. It's an action and a choice that you have to consciously make every day. You may not always be happy with the other person or they may hurt you or upset you; that's when you have to decide if you're going to move past the feeling and love them unconditionally. Many people assume that when the feeling is gone that love has died, but really that's not the case; it's just matured into something more complex and real.
That's how it is with Caitlin. I get excited when she's around and I get to talk to her; however, I also love her because of how Christ loves us and every morning I wake up and realize that I have to SHOW her love, not just FEEL it. I love her because of who she is and all the wonderful gifts and talents that God has blessed her with. It's blossomed into something so much more beautiful and it's wonderful. Hopefully that makes sense.