Goodnight, Mommy!

It's the first time in 11 years since my husband and I have slept alone without any kids. Last night, my youngest rocked off with her blanket and stuffies to sleep with her sisters because she wanted to. She's 6. My brain can't comprehend it. It feels like an empty nest and I feel like I've just failed motherhood. I know theoretically this was supposed to be a moment cheered but I just feel the loss of it. Where have I gone wrong that she would feel better off without me.. am I alone on this?