SIgh, here goes another supermassive-black-hole dense guy.
The "friend" immediately understands what is going. But the male lead? Not a clue.
... and the female lead is an idiot, she should just be honest instead of trying all these roundabout startegies....
Honestly, I can approve of this pairing due to the setup by the author.
He's not even considering her a romantic interest as he's just repaying a life debt to her and her family. He truly respects her, but that's about it. The thought of "she likes me" wouldn't cross his mind. Especially after being abandoned by his family.
She's also not going to confess directly because, knowing his personality, he'd accept only because it was something she wanted and as she said in 1.1, she doesn't want to force him through her standing as his master. So she's trying to get him to see her as a woman, instead of as just his master.
It's a fantastical plot and wouldn't work in a real world setting, but it works for the setting of this Manga.