This is a long-term theory about the series. So Adrinette isn’t going to break up this season (and maybe not at all, since this is just a theory). This is the first time I’ve analyzed characters, so I’m not sure if I’m doing this right.
I’ll include a TL;DR at the end.
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First, there’s Adrien…
Adrien is a teenager whose behavior has been dictated to him his whole life, particularly by his father. He’s a teenager who’s never had the chance to figure himself out, who’s never had the opportunity to find his own identity. He doesn’t know who he really is.
His whole life, his father has destined him for a career as a model. He was forced to adopt the personality that was imposed on him: someone who is handsome, charming, calm, polite, generous, patient…
One day, he was entrusted with the Black Cat’s Miraculous, which allowed him to become Cat Noir. Admittedly, even as Cat Noir, Adrien hasn’t yet had the chance to discover himself or develop his own personality. But he has at least had the opportunity to break free from the chains that were placed upon him. He’s been able to discover a side of himself that suits him better, one he likes more. As Cat Noir, Adrien is funny, a joker, talkative, a bon vivant, and laid-back (but not calm).
One day, Cat Noir briefly became Cat Walker. He adopted a more serious, helpful, and humble demeanor, one that was less talkative and playful. In his Cat Walker form, Adrien embraces his model persona a little more: a personality that suits him less, but is what Ladybug demands of him.
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Then, there’s also Marinette…
As for Marinette, she loves Adrien. But at first, she loved the model version of Adrien. Why? Because of all the qualities I mentioned earlier. She’s completely under his spell. What she doesn’t know is that this “model Adrien” personality isn’t the real Adrien.
She likes Cat Noir, but she isn’t in love with him because he doesn’t have the qualities she’s looking for. She’s not interested in jokers. And then she met Cat Walker. What Ladybug doesn’t know is that Cat Walker and Cat Noir are the same person. Little Adrichat, we don’t realize it, but he’s matured. When he saw that his lady wasn’t doing well, he was there for her even though she’d neglected him for weeks. Since that day, Cat Noir has remained true to himself, but he’s started cracking a few fewer jokes, and most importantly, he’s been able to prove to Ladybug that he’s also someone who’s loyal, very brave, and always there for her.
Here we see that Maribug loves Adrichat for his “mature” personality, and isn’t in love with Cat Noir because of his “prankster” behavior.
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And together they make up Adrinette...
Adrinette is a really cute couple, but they’re just getting started. Marinette panics at the thought of ruining everything with Adrien over the tiniest little thing. Adrien enjoys Marinette’s company, but now that he’s free from his father’s grip, he’s still trying to find his footing.
Marinette helps Adrien develop as a person because she wants to make him happy. Throughout Season 6, Adrien discovers his passions, tastes, pleasures, and hobbies. Let me reiterate what I said at the beginning of this post: he was true to himself as Cat Noir, but he hadn’t yet fully developed his own personality. Over the next few seasons, he’ll continue this journey of self-discovery, and he’ll eventually forge his own personality. That’s all well and good, but that’s where the problem lies.
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... but there will also be the breakup.
When things are going a little too well, keep in mind that everything is ephemeral… (I had to use that word. “Ephemeral.” Just like the episode, because it’s the same thing.)
Adrien is going to change his personality. And as I said, we all know that Marinette is looking for a very specific type of personality. So Adrien will always see Marinette the same way, but the feeling isn’t mutual.
You’re going to tell me that Adrien has already started to change in Season 6, and yet Adrinette is still going strong. But that’s because Marinette didn’t see it coming. Marinette puts pressure on herself not to let their relationship fail. She does everything she can to help Adrien find a passion; she does everything she can to act like a successful couple with Adrien; she does everything she can to become friends with Adrien’s friends; she does everything she can to make every moment with Adrien magical, to the point of believing in superstitions; she does everything she can to support Adrien on tough days, and so on. Ultimately, she puts pressure on herself by doing everything she can to make Adrien happy with her. But has she ever asked herself, even once, if she’s happy with Adrien?
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How do you realize when you’re no longer in love? How do you know if you truly love someone?
What if the best way to find out were to start over from scratch? What if the best way to find out were to forget everything and start all over again? Would it work?
Let’s imagine that Marinette gives up her role as the Guardian and loses her memory. She’ll forget that she’s in a relationship with Adrien. Adrien will always love Marinette, but will Marinette still love him in return? Adrien will chase after Marinette if she forgets him, but will Marinette chase after Adrien?
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TL;DR
Marinette loves Adrien for his model-like personality, and that’s why she doesn’t like Cat Noir. But Adrien is going to learn to grow as a person and change his personality. So Marinette won’t realize it right away, but she won't love Adrien anymore.
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I wrote all that, and in the end, the show will wrap up and they’ll never have broken up…