The Seven Deadly Sins are a band of knights in Britannia who disbanded ten years ago after being framed for plotting a coup of the Liones Kingdom, the Holy Knights who sequestered them before seizing control in the aftermath of a rebellion they organised. Elizabeth Liones, Liones' third princess, locates the Seven Deadly Sins' leader, Meliodas, before searching for his comrades in order to clear their names and free Liones from the Holy Knights, who were duped by a demon named Fraudrin into releasing the Demon Race from their prison.
The Seven Deadly Sins has a couples problem in so far as, all the primary romantic couples of the story are problematic, toxic or plain boring and in some cases illegal out in the real world. Let’s get into a deeper dive of 4 primary couples shown on the show
1. Gilthunder and Margaret

This relationship isn’t as toxic as it is a non-ship. When Gilthunder was introduced as a character he seemed like an interesting one. His determination to kill Meliodas at any cost was intense and intriguing. However, it turned out that was all a ruse he was making up to protect Margaret. After that revelation, Gilthunder probably became the most vanilla character on the show.
Although, if there was one character that could beat Gilthnuder at being boring, it would have to be Elizabeth’s sister, Margaret. The most interesting aspect of Margaret was the time when she became the vessel for Ludociel. What do you get when you pair up the two most basic, devoid of personality people in a romantic setting? You get Gilthunder and Margaret. I don’t even have anything overtly good or bad to say about them because that’s how boring they are as a couple.
2. Elaine and Ban

Only Seven Deadly Sins would take a too cool for school, outlaw character and turn them into a mopey one-note mess. Yes, I am describing Ban here. Being one of the characters that actually manage to live up to their hype, I had great expectations from Ban. However, the weakest aspect of his story turned out to be the romance part.
Getting to the toddler-sized elephant in the room first, Elaine looks 9. She may be a thousand years old but she looks 9 and Ban looks at least like someone in his mid-twenties and their relationship is wrong on every level because of this.
I cannot look at any pictures of the two of them without cringing to my bones. Even if we were to ignore the weird age/appearance thing here (which we never should), the two do not make sense as a couple. Elaine’s life was the cost for Ban’s immortality. Ban swears to get Elaine and would go to the end of the world to get back the love of his life, whom he fell in love with within a week.
Don’t get me wrong, such intense, ride or die relationships on screen can be very fun to live through. However, Seven deadly Sins has a knack for making otherwise fun things dragging and repetitive and dull. The show keeps telling us how epic Elaine and Ban’s love is but because there was so little groundwork laid out for the two of them, the whole thing feels just a little bit off.
3. Diane and King

Age is a fickle and strange concept in Seven Deadly Sins. However, there are no amount of liberties you could take to describe Diane’s relationship with King and not make it creepy. To recap, Diane spent a few hundred years of her childhood playing with an adult (but childlike in appearance) King who has lost his memories. During a game, Diane makes King promise he would never leave her. Over time, King begins to regain his memories, breaks his promise and goes back to his fairy kingdom. This time Diane loses her memory of growing up with (or practically being raised by) King.
Years later, when the two of them are in the Seven Deadly Sins, Diane has no recollection of her childhood memories. Eventually when Diane's memories return, she and King kiss, and they become a couple.
If you need me to spell it out for you, an adult took care of a child growing up and then dated the child when she became an adult herself. The memory loss aspect of this does not make it any better. However, even if we were to ignore the weird grooming aspect (which again, we really shouldn’t), their relationship is very one-note.
While watching the show, to me it felt like they were pairing people up in the story and Diane and King ended up together since everyone else was already paired up. This isn’t something unique to Seven Deadly Sins and could have turned into something interesting. Even though Diane and King’s actual relationship is kind of sweet, it would have made more sense to keep it platonic through and through.
4. Elizabeth and Meliodas

Meliodas is the eldest son of the Demon King, Elizabeth comes from the clan of Gods. While war rages between Demons and Gods, Elizabeth and Meliodas fall in love, they are cursed for it. Elizabeth is cursed to be born human, unaware of her powers and her love for Meliodas.
The moment she recalls her true nature, she dies quickly thereafter. Meliodas is cursed to a life of eternity and crossing paths with Elizabeth, watching her die over and over again. On paper, this is the perfect tragic central epic love story that drives the entire story.
There are a few hiccups though. Meliodas is very pervy around Elizabeth from the beginning of the show. He has no shame in touching her inappropriately without her consent or stealing her underwear. Keep in mind the Meliodas at the beginning of a story is practically a stranger to Elizabeth. It is supposed to be funny but I just have one question, to whom? Even creepier, Meliodas watched over an infant Elizabeth. There is something really deeply disturbing about a full-grown man holding an infant in his arms and screaming, “don’t you dare lay your hands on my woman”

In conclusion, The Seven Deadly Sins started out with a great premise, it lost its edge as the story progressed. While there were some truly memorable moments throughout the show, the relationships that were meant to hold the whole story together, fell short. Most of the relationships seem to follow the same notes and after a while end up becoming a snore-fest, if they aren’t being extremely inappropriate.
If anything, The Seven Deadly Sins has taught me, you can turn any two characters into a romantic pair by turning their cheeks red, putting on romantic music in the background, putting one of the characters in mortal danger and if nothing works giving them a backstory where one of them is an adult and the other an infant.
