In an interview when you get asked a personal question about your secret life like"are you in a relationship or no" What would you say??

I would tell the truth. Why not? From my point of view, if you are single , the answer might be positive because the HR would think that you have absolute availability (national and international).

i would say either i am in a relationship  or not thas wont effect my work or my dictions since i agreed to .have a career 

telling the truth is the best way always :)