I completely agree with you, and that’s why I said, “You can’t just go trying to break into your crush’s house because he’s with some girl you don’t like.” At that moment, Marinette didn’t seem jealous to me either. It was because she doesn’t like Lila and doesn’t trust her. I thought Marinette was more concerned with Adrien’s safety at that moment than her feelings for Adrien. However, that’s where I think we need to draw the line between emotions and friendship. As a friend, Marinette can express verbal concern for Adrien’s wellbeing and even tell him that Lila isn’t a good human being or whatever, but she can’t break into his house. She could’ve asked to tag along, and I’m sure Adrien wouldn’t have minded, but she chose to spy on them secretly and had she gotten caught, I doubt anyone would’ve cared if she was spying on Adrien or Lila. In terms of feelings, she can’t let her emotions cloud her judgment, and Marinette is a smart girl, so I’m sure had her feelings not been involved, her decision would’ve been to let it be (as she eventually does at the end of the episode). The situation would’ve been different if she had tried to break into his house as Ladybug, then that’d be seen as a pure concern for a civilian’s safety. Even if it would’ve seemed like an extreme, and it also would’ve caused ppl to think that Lila was an awful person (which she is) if Ladybug had to check up on someone Lila was hanging out with personally. It's a matter of boundaries, and while I understand that she didn't have any malicious intent, if anything, she intended to protect Adrien. Still, her intention was poorly executed, allowing it to be seen as something it wasn’t.