
No, he becomes more merciless and akin to something like a demon since his body is actively channeling energy or spirits from hell.
The only reason why he's acting that way towards Myungha is due to the hex on Myungha's back. Before he showed up the prince was more into beating or killing people as he pleased. It's not like he was going around raping his guards or the other palace workers.
The hex causes both Myungha and the prince to be drawn and crave contact with one another. It's why the initial warning to keep his door locked at night and to never step outside failed. Myungha was being drawn to the prince just as much as the prince was to him.

No problem!
I've been seeing people either get confused or angry thinking the curse turns him into just a rapist when it actually just basically makes him closer to a demon. His body is acting as a gate for malevolent spirits so in turn his mind and body are being warped. The reason why it's worse at night is due to folklore/mythology equating nighttime to when spirits come out the most.
So what's the deal? He just becomes a horny monster at night??