Is it ever explained why Helen berates Harold all the time?
Cuz she is a total represed bitch maybe?
Actually the game does explain it a bit, but does an excellent job of letting the characters gloss over the ugly bits like a person would in real life when being asked to air their emotional baggage. It was a bit of a snowball effect. Harald used to be a rough around the edges all-around good guy with a rougish badass side, and that was the man who Helen fell in love with. Helen was a wide-eyed innocent who found the excitement of the "bad boy" intoxicating.
But that relationship dynamic diminished into middle age, as it does. At the start of the game they're both very bored without any real life destination, they're just going through the motions out of duty towards being good parents. Their daughter, Mia, knows that they're not happy but doesn't realize that they feel dead and trapped in their "meaningless" suburban lives.
Harold spends enough time at the precinct that even the Police Chief will mention Harold needing to spend more time with his family in an off-hand comment. And Helen has turned to religion in hopes of giving a sense of purpose back into her life, and when that failed she doubled down until the original goal of religion was lost in the zealous pursuit of obedience...or at least the appearance of obedience.
The Nun has a very sideways approach to psychology, but she does in fact point out exactly what Helen is missing in her life and how she needs to reconnect with her husband on a personal level again. Harold doesn't need to be schooled to get an attitude adjustment, he just needs to stop feeling sorry for himself and dig up some of that lost tough-guy ambition. That's how even if the MC decides to take Helen for himself at the end of their quest he is still found attractive enough that his partner easily replaces Helen for his romantic needs.
The real point and beauty of their story arc is them realizing the illusion that they've been living meaningless lives. Living has less to do with what you're acomplishing and more to do with how much you love what you do.