It's always been that way, although I don't think it's the same in lower difficulties.

It only lasts a certain amount of time. Once the spell wears off, the NPC will turn hostile, upset that a manipulative form of magic was used.

However, if you're not around the NPC when the spell wears off, the NPC will get over it. Meaning you can talk to them again later as long as you're not right there when the effect ends. Walk away, come back, everything's fine.