What does "in love" mean?

Last night before finishing out the bedtime routine, Gabe gave me a big hug and said, "Mom, am I your sweetheart?" to which I said, "OF COURSE you're my sweetheart!!!" He then asked me with a serious wiggling of his eyebrows, "Mom, what does 'IN LOVE' mean?" I started laughing uncontrollably, and I said, "Well, that's different hon. I love you, but I'm IN LOVE with Daddy. When you're IN LOVE with someone, you want to marry them." Gabe said, "I love you too Mom, and that's okay, 'cause I'm in love with Kendall." I said, "YOU ARE??? Is Kendall your girlfriend?" He said, "Yep and I married her too." I was still laughing when I asked him to make sure he invites me and his dad to his next wedding.... KIDS!!! They ARE hilarious!!!!