Don’t start making excuses. By and large, your personal life of the curious is not concerned at all. Do not respond with rudeness or aggression, showing that you were hit for living. It is best to make a joke in this situation, having said, for example, that at the knight the horse has limped off, that it gets so long. You can start talking about all your unhappy relationships, while giving the will of fantasy. Usually, this confession shocks the interlocutor, and he understands that he crossed the border of the permissible, asking such tactless questions. Finally, you can honestly say that you don’t want to talk about it.
A good way to solve the problem is to answer the question while putting the interlocutor at a dead end. Let him feel like being questioned. He’s not likely to want to dig into your personal life after that. Don’t be afraid to offend a person if they do the same about you.
It happens that a person asks a non-stactless, inappropriate question for you, just without thinking that it might be unpleasant for you. If you know your interviewee really has that habit, don’t be offended, but just skip his words past his ears. Don’t look for hidden subtext where there isn’t one. You can get into such a situation by lapping something unpopade.