This seems to be a morality play
I've seen so many Boards with old posts cleared out, I'm surprised that this one only has two and they are both from 2008. I hadn't seen any of this trio of movies (the 'Our X Y' movies) before and caught this and Our Modern Maidens last weekend. I didn't see the very beginning of Maidens, but really enjoyed this one and what I saw of the other.
I think this one is a morality play, the girl who takes her time, isn't boy crazy or 'fast' is the one who ends up not broken. This is interesting in light of the earlier Maiden movie, where Joan Crawford's character basically throws herself on the grenade - leaving her brand new husband during the reception after telling her Dad it was just all a mistake because she finds out that her best friend is pregnant by her husband. This opens the door for an annulment so that her best friend can escape the scandal of unwed motherhood, but taking the scandal upon herself.