I reckon Chris met someone else more on his level intellectually who is not a selfish slob and broke things off with her, hence the desperate Travel Inn bathroom selfies and pretending she's smart enough to be a doctor whilst hanging out with a load of sixth formers. Anyone who bangs on about how joyful their life is on social media is usually full of tit. She's giddy from all the dick she's getting now from her tiny new boyfriend, but how long will it realistically really last? They don't live near each other, she has two small children, and is supposedly going to medical school, it's just not sustainable so why is she desperate to mention her new relationship so frequently and publicly? It's so embarrassing!
Hope he's prepared to be sent out at all hours to fetch Hannah more chocolate whilst she lies on the sofa, greasy, surrounded by crumbs and discarded wrappers whilst playing Theme Hospital, because that is about as close as she's getting to becoming a doctor.