How funny would it be if the reason why Adrien (16) sees Marinette (15 and a half) as only a friend because he's actually married?
Let's say France allows 16 year old's to marry with parental permission and Gabriel allowed (made him obey by the ring) to marry Lila. Her mother gave permission, but it's not Madame Rossi, it's Tomoe Tsurugi which seeing as it didn't work out between Kagami and him, decided to use her second option.
The thing is, they done it in privately, as in not publicly to not damage Adrien's and Lila's model careers (thankfully it's not as bad as with korean idols), but they are pretty much husband and wife in the eyes of the law.
"Oh, but Adrien wouldn't be in love with Lila because she's a manipulative liar!" And Adrien is not a pushover, so I'm sure they talked a lot about what they want in this marriage and Adrien made it crystal clear he wants an actual partner in life, someone who would love him as he really is, not just someone who would call him theirs.
Surprisingly Lila didn't want there to be any secrets between them. So if he agreed on that, she agrees to be better than Audrey to Andre.
They talk a lot and learn much about eachother.
Lila is actually Cerise, Adrien stopped liking modelling. They both hate his dad, but like Nathalie. Bit by bit, sleepover date after sleepover date they get confident in eachother because they know the other deeply. Cerise likes Adrien because he's the only interesting one around, she saw him as just a cane, but he turned out to be a hidden sword. Meanwhile Adrien likes Ceri because of how determined she is, it looks like nothing short of death can stop her.
In public they are still just "friends" and coworkers, but now Lila's hate of Marinette is justified because how dare that bitch try to get her husband???!
Also imagine if it comes out that Adrien has (used to have) a crush on Ladybug? Marinette is a half devastated, half happy because maybe if she tells him she's Ladybug it all will be great?
"So-o-o... You like Ladybug?"
"Y-yeah?" Adrien is taken aback, but has to keep cover.
"What exactly do you like in her?"
The thing is, crush on Ladybug ended when he fell in love with Cerise, so he looks away shyly (from Marinette's standpoint) and unbeknownst to her looks at Lila.
"Well, she-uh, she's very honest? A-and pretty, and confident?" Wifey's radar (fox ears) pinged, so she bee-lined to where they were and sat across him.
"Oh, really? That's interesting, tell me more!" One thing she loves is teasing and damnit did he have to say this where she heard?
"Oh, it's nothing... I mean, I'm just a civilian and she's a hero?"
"~I'm pretty sure she'd love to hear what You have to say, Monsieur Paris #1 model~"
"You know, it's just a rumour, but I've heard that Ladybug has a crush on you too!" Marinette added in a faux whisper. This time Lila started to blush.
"Oh, does she now? Tell me more." Just as quickly as she came, Lila left, but not before Adrien looked her right in he eyes.
Whatever is going on here? Marinette has no idea what that is. So she leaves very confused when the bell rings.
Plot stuff happens as it did, Gabe kicks the bucket, but this time Adrien has Ceri. When everyone starts to parrot Ladybug's lie he confides in her and that's when she decides to don the butterfly and end Ladybug for good.
Not just for her, but for them.
Obviously she tells him, it was her who insisted on truth being fundamental, but he surprised her by telling her he's Chat Noir. Not a day without Adrien's life being worse than previous, huh?
"I'm still going to be a hero."
"I would never ask you to stop, it's so... You after all."
"What's that supposed to mean?"
"Oh, please. You're a people pleaser, others always come before you for you. You're very kind and way too forgiving so no wonder you are a hero."
So then Chrysalis enters the fray, but then after she fights the heroes something like this happens:
"You may have won today, Bug, but some day it will be over for you."
She turns to leave, but then stops, and turns around again looking at Chat Noir this time.
"Oh, almost forgot, Mom called and said she won't be able to come, so the dinner tomorrow is cancelled, sorry."
"I get it. Tuesday still a movie night?"
"Of course honey. Love you!"
"Love you too!"
"..."
"... Dude, what the hell did we just witness?"