This happens in Germany.
Work culture doesn’t fit my personality: I don’t talk much, I keep to myself, I simply want to do my job and go home, I separate my personal life from work, my colleagues are full fledged gossips, ignore the duties that need to be done and then expect me to help them when they are late. I don’t have patience for that crap anymore.
Due to internal regulations, I have to stay on the unit for 4 weeks after sending my notice. Answering honestly the question of why I’m quitting would ensure that they yell at me and bully me, and I don’t want to experience that again. Even saying ‘it’s none of your business’ ensures that they feel insulted and start yelling. I have decided I don’t have patience for people like that anymore.
So, what do I say?
Say you are working for a family member (helping your dad with his company or sth.). A colleague once had to go help his parents with their small company and no one questioned it a bit. No “better pay?” or “man you are moving far away!” just “oh, well good luck”.
"what kind of businesa is it? what are you going to ne doing there? when will you be back? " etc, etc, etc. this and a lot of other responses [lies] in this thread will invite pletora of questions from gossiping types which is what op is trying to avoid.