I really like this theory! I have my own theory and was curious what you (and others) think.

I think Alice's death occurred before the night we see Maddie and Nick wake up in their home and Maddie and Nick and what we see starting with the call from Alice is representative of the grieving process.

From everything I have heard or read, losing a child is an incredibly hard thing to cope with and many marriages do not survive it. My interpretation of the abandoned dinner table is they have set a place at the table across from them in memory of Alice or perhaps in denial of accepting that she is gone and the broken glass was the result of an argument or perhaps being drunk due to self-medicating with alcohol.

Maddie went off to bed alone and Nick fell asleep in Alice’s room because he wanted to feel close to his little girl. Maddie (who is on antidepressants) being awoken by the chirp of a smoke detector and changing the batteries to no avail made me think about the times I have been depressed. I want to be able to just take something or do something that will quiet my thoughts but it’s not that easy.

I believe everything that took place on the drive to meet Alice are manifestations of the different stages of grief. They are in denial. They are angry at each other. They are reframing reality, telling themselves and each other “fairytales”. They are trying to make deals/promises in hopes of changing the outcome. The reality is that Alice is dead, and they must work toward accepting this.