Unpopular opinion but I really don't like the idea of the love square developing through Marichat or Ladrien dynamics.
There is an imbalance with those two dynamics that put me off when it comes to romance. It's okay for brief friendship moments or to feed into the overall love square dynamic, but not to develop independently from the other ships.
With Marichat it means that Marinette has knowledge of Chat's love for Ladybug that she shouldn't have and also, obviously, the knowledge that SHE is Ladybug that gives her an advantage and imbalances the dynamic in her favour. Plus in order for it to work independently she would need to continue to reject him as Ladybug which comes across as a bit cruel and deceitful.
With Ladrien both parties prefer to interact in their other identity (which is why it's normally pretty awkward to write). This means that one of them would be making a conscious choice to interact as Ladybug/Adrien and the most obvious reason to do so is because one of them discovered the feelings of the other and wants to take advantage. Which is already off to a pretty imperfect start.
Don't get me wrong, it's not that having them interact in all identities is bad. Nor would it be bad for them to discover things they liked about the other when one of the dynamics throws something up. But to focus on developing Marichat or Ladrien whilst excluding Ladynoir or Adrienette really doesn't vibe well with me. With Ladynoir and Adrienette the feelings might not be quite mutual but the knowledge they share is more balanced. And with regards to their feelings, Chat Noir knows and doesn't mind that Ladybug knows his heart and Marinette is actively trying to hide her feelings to the oblivious Adrien. Which keeps things more...fair. To develop Marichat or Ladrien over several episodes would mean actively tanking Ladynoir or Adrienette at the same time in order to keep the interest focused on the identities that don't naturally interact in a daily basis.
In the same respect, it also bothers me when there is a one sided reveal and it gets played our for an extended amount of time. I think it's a breach of trust and it makes me glad that the Cat Blanc relationship isn't going to be the canon way their relationship starts.
FYI I have read fics that have been good and enjoyable despite it being one of the things I've mentioned. It's just not what I seek when fic browsing and not what I want to see in canon.
Also FYI but I also like that the show canon isn't always perfect and with good dynamics, either. Because they show the kids making mistakes and paying for them (Chat Noir's jealousy and how it makes things worse, Marinette's jealousy and OTT tendencies backfiring on her etc) and in the end they are just teenagers.