Sheila loathed her mother,that's why she'd told everyone that she came into contact with,including her psychiatrist. Latterly,it would have seemed that Neville had been out of favour too because he was supporting June and her fragile state and seemingly siding with her to keep the peace.Gone would be the long phone-calls in the early hours when Sheila would pour her heart out to her father.
I suppose Sheila got to such a pitch that she'd felt that she didn't have anyone.