Well, fair enough. Obviously I see a lot more romantic development between them then you do, but it's not worth squabbling about. I still think it mostly comes down to expectations. I see a slow build up of trust and affection that will (probably) eventually blossom into something more, but obviously Hayate isn't just going to up and decide he really wants to make out with a 13 year old. Heck, even Maria jokes about that being a very bad thing, and she's a Nagi supporter all the way.
And that doesn't stop them from hitting all the romantic comedy cliches. Nagi has kissed Hayate twice, had Hayate walk in on her naked twice, ect. They get tossed into these sorts of situations all the time, no matter how much Hayate insists he's totally not a lolicon.
Alternately, to reuse an old joke of mine, nobody likes their little sister
THAT much.
