About Sylphy, i've already pointed that and it is confirmed every chapter.
Rudeus is not that dense (or he still would be a virgin at this point), but Sylphy in fact is.
Yes, i've read the novel until this arc (please do not comment about it here) and i'm not satisfied.
- What she expected 1st? Rudeus to instant recognize her and an emotional reunion. Ok, it didn't happen and she feared he forgot about her.
- But then she already (by the wrong signals, lol) confirmed that she was not forgotten by Rudeus and, more important, that he still have the same personality she loved back.
- More, with the Princess help, she know a lot about Rudeus today and what happened to him.
So, the big obvious question is:
If she still trusts Rudeus, WHY do not reveal her identity to him?
- He would imediatly understand her situation and help her. They could stay closer like in the past. Even if Rudeus (obvisouly due his situation) does not fall in love for her at the sight, by time it would happens anyway, since they fatally will become so close again.
It was a rhetorical question! We know the reason. Silphy is the vacillating nerdy boy trope here.