Ml Destruction - Tumblr Posts
I LIVE for the contrast between Adrien realising he is in love with Marinette and Marinette realising she is in love with Chat Noir.

Adrien: I think I am in love.
Literally the next scene, Marinette:

Marinette: It's a disaster, I think I am falling in love.
For Adrien, realising that he loves Marinette is wonderful! Of course he loves his very good friend Marinette, who else would he??!
But Marinette is absolutely devasted by the realisation that she loves Chat Noir. Maybe she feels like she has failed on her duty as Ladybug to not let her emotions impact her work. Maybe she feels guilty for rejecting Adrien's love just to realise that she is in love with Chat Noir. In any case, it really pains her.
If we take a step back; in the last four seasons, it was Adrien who was suffering of his love for Ladybug. He cried over her in Glaciator 2. Loving Ladybug pained him, while Marinette, albeit somewhat disturbed by her fear of rejection, hadn't suffered as much so far. Maybe she was repressing it, but that's not the point.
The point is, seems like whoever likes the superhero gets their heart crushed: their duties prevent them from knowing the identity of the person they love (hence causing the whole love square schenanigans) or from loving them freely due to distraction, or worse, risk of destroying the world.
I feel like a broken record since I keep repeating that it is their superhero duties that cause them all the pain, but it seriously is. I think the writers are preparing the base for the Kwamiis Choice, where Tikki and Plagg also realise that and decide to free them from the burden of being superheroes.