I imagine that generations ago, even in the US and Europe a similar scenario would have been common. Their age difference had less to do with it, I think, than gender and their culture, which frowned on men and women getting to know each other outside of an arranged marriage. They were both more traditional than they realized, while imagining themselves a modern couple simply because they chose their own partners. Neither of them had romantic experience to bring to their relationship.
Farzad thought of Amineh as an educated woman with (when they met) career aspirations of her own, which he welcomed in theory, but yet he did not expect this to conflict with his traditional assumption that his own work would take priority. He did not yet know her well enough to have discovered how fragile was her self-esteem, nor in his inexperience did he realize that women tend to place a higher priority on emotional intimacy.
Amineh had romantic notions about love along with her emotional neediness, and like most women she expected from Farzad at least the kind of close friendship that she had with Ava. She did not have the confidence to assert herself or express her needs, nor to pursue her original ambitions.
It was unrealistic for them to expect that everything would fall into place on a honeymoon—relationships need much mote time.