"Nana died," Mom said, calling for the first time in a year. But it's not the dead Marty Jones mourns she's more concerned about the departed. Now she must get in a car and drive cross-country to Arizona with her mother and two sisters, all perpetually pre-menstrual, all who hate each other. As if this estrogen-drenched bitch-wagon wasn't bad enough, Marty has to deal with meeting a side of her family she hardly knows and fraternizing with a convicted murderer-uncle isn't in her repertoire.
Meanwhile, Marty's boyfriend Peter is no help. He stares blankly at her while she packs and slips an engagement ring into her suitcase while she's not looking. Peter doesn't know what kind of family he's trying to join, and finding the ring just adds to Marty's troubles. Phoenix is 65,000 words.
They don't have airplanes? You put in the road trip cause you need it for the novel, not cause it's what anyone would actually do. This screams contrivance. The way you describe Peter makes him seem unhinged.
This is a mess but don't blame the hook.