To be honest, I don't want Nagi to be win this bet. Doesn't matter though cause she'll win 100%. That's how predictable this manga is. Because it's so predictable, there's bound to have some kind of twist in it. To me, Ruka letting go of Hayate because she lost is a big fat lie. If it's truly real love, there's no way a single bet can get rid of that. For the first time in her life, she found someone she can rely on, and you expect me to believe that she'll move on just because of some fucking bet? And if she did win and goes back to the mansion, that kinda defeats the purpose of why they are in the Violet Mansion in the first place. You won once, that won't change anything. A single victory can't change a lifestyle of a rich brat. Even now she still has that trait. Going back will make it return thus we're back to square one.