Why do all the fans want Adrien to get jealous? Marinette's jealousy is disruptive. Wouldn't Adrien's jealousy be written the same way? If not worse as Chat Noir is terrible at being rejected?
I think it has less to do with the jealousy angle and more to do with Adrien Realizing Some Sort of Romantic Feeling for Marinette angle.
Because if they brought in Rivals to help the love square, that’s what should happen, right? Isn’t that the whole point of bringing in alternatives, so that it spurs someone into action? But of course they couldn’t even get something as basic as rivals right.
Luka as a concept works. He’s in love with Marinette, the side of the love square that goes ignored, and he actually sticks around. However he doesn’t work in the actual text because 1) He doesn’t actively pursue Marinette (seriously, just because we see how they are alone together, I don’t even really know why Adrien is so sure that Luka and Marinette are into each other except that sometimes they stand next to each other) and 2) Luka has done nothing to challenge Adrien’s perspective. Adrien doesn’t get sad or angry or jealous about the thought of Luka and Marinette being together. If anything, Luka just proves that Adrien regards Marinette with zero romantic inclination.
Kagami as a concept doesn’t work. She’s in love with Adrien, but so is Chloe, Lila, and apparently 100% of Paris (gender, age, and sexual orientation apparently mean nothing in mob form). Bringing in anOTHER obstacle for Marinette isn’t going to change her behavior because Marinette doesn’t need more encouragement in pursuing Adrien - she’s already trying her best. In her current position, the only thing Kagami could’ve brought to the table is by being a Not Awful Rival (someone Marinette would have to acknowledge as a good fit for Adrien) but 1) Kagami has the most inconsistent characterization in the show and 2) All that would do is make Marinette give up. If they wanted to make Marinette learn something about her feelings, they should’ve made Kagami in love with Chat Noir.
Fans want Adrien to get jealous because that would mean he felt something. If he didn’t like some guy hanging around Marinette, it would mean that something has changed in the way he looks at her, especially because we know he’s capable of jealousy and it’s not pretty. As is, he’s way too calm which just means he feels. Nothing. And we’re 3 Seasons in, what the fuck does that say about the Love Square as End Game? At this rate, the only reason Adrien is going to be in love with Marinette is because she’s Ladybug.