No, shuzel and her mostly had good chemistry yet you'll see the difference in like three hundred chapters that shuzel and the youngest seems to notice how different the king and MC's relationship with each other is. if you read the novel it's mostly the king thinking of making her his partner. And he's the one who keeps teasing her and making her blush but when it comes to shuzel, it's all about food because he liked sweets if I'm not mistaken
The translations were cut off and there's currently no official translation but I read the raws here https://ncode.syosetu.com/n7222ff/
Yes, we have a male lead but it's not yet confirmed. However, many novel readers are saying that the male lead is going to be the King, of course. And as a novel reader myself, I did see their chemistry and how she blushed in some articles whenever mc was talking to him. So yee, black haired dude is the male lead and she does lose weight but it was slow. And she also gets a dragon, and every dragon lovesn her because of how she treats them like making rooms for them and what not, changing their views on the right way to tame a dragon.