This was somehow already anticipated, that something bad is going to happen, since pretty early in the manga. Anyways, back to fill chapters, been noticing that the manga is getting more and more slow paced, or is just me?
I have no idea why people are always assuming horrible things. This has been a cute romance manga for 99% of the time. I don't think the author is an asshole enough to suddenly turn it horribly grimdark.
@Shinketsu I think it's just you. Really, for a long time there basically was no plot advancement, or plot really, at all. They were just noodling around. Sure, he had a curse, they were thinking someday it would be nice to break it, but they had no strings to pull on and were doing diddly about it. It was mostly duke + maid being lovey-dovey and the other characters being silly (not that I minded). Now in the last while we've had ultimatum from mom, a couple of major witchy people conspiring to mess with them, a genuine attempt to break the curse which of course failed but gave them a lead about who cast it in the first place, and a lead how to go find out more which they now propose to follow. Almost every chapter lately is doing something to advance the plot.
Alice's mother is the one who cursed him. The reason is to made sure he doesn't get close to Alice and made the same mistake her mother (The grandmother of Alice) whom if you know from earlier chapter had a bit of romance with Duke's Grandfather. She (Alice's grandmother) probably got killed because of it, out of jealousy (Or cheating?) from duke's Grandmother, she probably even call her a witch for shits and giggles. This road imply Alice's mother isn't a huge bitch and is actually a kind hearted person and are only doing this for the sake of Alice. The other likely possibility is Alice's mother being a huge Bitch and just doing all of this for revenge, although this is very unlikely to happen seeing how that she has always been seen being very kind hearted.
This is only two out of all the possibility the writer can pull, but this is the two I could see most likely to happen from the evidence we got (and some gut feeling).