To assume that nobody saw this problem coming is a bit strange, given how it was properly foreshadowed. You're basically saying that the people expressing their dissatisfaction are somehow retarded.
The problem isn't that an argument over the nature of their relationship happened. The problem is that Issei is the only one receiving flak for this even though Rias is also guilty (and more so imho). Also the fact that nobody explained what was going on, even though explanations are in order here.
|