I get why Leniel is worried. Giselle is inherently nosy and gets involved in things because she cares about people. But she's not cautious and always puts herself in danger. Leniel who's also naturally possessive, can't help but lock her in his mansion since she tends to run into chaos. However I understand Giselle as well. Being locked inside without having the freedom to go outside can be suffocating. It's not a nice feeling that you're basically a prisoner caught by a yandere man. So I just want them to find a middle ground.