Margaret is attracted to Henry's masculinity. She is, in Edwardian terms, an old maid and although in her philosophy she is progressive, she becomes submissive to him, albeit somewhat reluctantly. She is passionate in philosophical terms and Henry has awoken her physical passion. In the book, if memory serves, she says that she has had proposals before but only from 'ninnies'.
One of the themes of the book is the beginning of the decline in Victorian society and the coming of a different age represented by the use of motor cars, city development, the increase in business and commerce. Mrs Wilcox provided a bridge between the two "worlds" and now Margaret may perhaps take on her mantle. The natural world means much to the Schlegel women and Aunt Juley - the Wilcoxes ride through it, own it etc. They are very concerned with image ('It's not the best part of Shropshire', said by Henry as he surveys the parkland beside the Oniton house).
Helen is young, idealistic and impetuous and has not sufficient maturity to see the damage caused by her well-meaning meddling. Leonard is desperate to better his life through reading, music etc but is dragged down partly because of the Schlegels and partly through his own naivety. Through him Forster describes the rigid class structure and the paternalistic attitudes of the bourgeoisie.
Evie and Dolly are the conventional counterpoints to Margaret and Helen. Surprised to see Evie sharing a cigarette with Charles! Can't remember that in the book.