It's funny the guy has to """"work"""" really hard for the girls while his sister (a less deserving character) gets all the dudes barely breaking any sweat. I hope the upcoming arcs aren't a drag like this one felt.
His sister tried really hard to work to get them away after she realized the five idiots are idiots. Leon was just doing what he wanted and got the girls by trying to get a better ending for them. Both of them fail at their blank aspirations.
It's just so annoying that the author forgets what he is making fun of. Making fun of harems and then subverting it with a polyamorous throuple. It's the only series I know that does this. Too bad the author gets a lobotomy or something.
You've really missed the ball here, haven't you. And terribly misread the signs if you didn't expect Leon to be entangled with Olivia and Ange. This was never an anti-harem joke, but about how terrible the five love interests are at their jobs, even if they are very attractive.
In both their cases their attempt at an easy life came from doing some amount of hard work. Leon risked his life to get into a position where he had little responsibility and could live easy. Societal expectations pushed him to try to find a woman. His empathy and knowledge of the story made him help both Ange and Olivia. His efforts to help the women he gets engenders their favor. His punishment is how much responsibility he takes that he doesn't want even if he very really could have just exited the kingdom to live on Luxion.
Marie tried to get her harem, and in doing so get out of debt as her new family is poor. She did work hard to master enough healing magic to replace the protagonist and remember enough of the story to take the role of Olivia's saint hood. The five idiots do love her, she knew the 'flags' that would attract them. But since she basically had her brother play the game for her she didn't realize the pitfalls she was walking into. Besides that they have no sense of money and since she isn't actually the Saintess, the only way for them to really marry her was to leave their noble connections. Her punishment for being selfish is having to deal with her harem of idiots because she wanted to be loved and have money. It's still a better life than she led prior, but she has to be responsible for the gaggle of idiots.
So wait. Olivia and Angelica both love eachother. And they both love Leon. WHY DID THEY SLAP HIM?
They were smiling because they knew he'd be an idiot, but the guy proclaiming he loves them both is a bit of a non-answer. Just because you love someone doesn't mean they can't be an idiot. Leon knew his answer was slap worthy, Marie knew the answer was slap worthy. It doesn't mean any of the characters involved love each other less.
Honestly, a major character flaw that Luxion always points out is that Leon has a habit of running away from the situation. Another is trying to keep things on rails to the scenario as best as possible without realizing his actions in story are making him the central to the game's ongoing plot. Well that and his behavior attempting to avoid realizing his own romantic entanglements. So his answer was that of a two-timer, and was like he was running away from the situation. And he was running away a little bit. It causes issues farther down the line.