When your partner asks, "Where were you?" is it always necessary to tell them?

I stumbled upon this while surfing cool on one of our relationship forum loveshack.org and it tickled my feelings, I would like make some clarification on certain points raised.

Hope to get your audience as we proceed. 

So say you're in a relationship with someone. Say every time you come home a little late or something they ask,"Where were you?", you should always calmly tell them where you were, right? Because in all honesty, if my S.O. kept asking me that, I would be a bit annoyed because it would feel a bit nosy on her part, but at the same time, she's my S.O. Communication is necessary for a successful relationship. So the best thing to do would be to suck it up and just tell her where you were, right? I would be annoyed because it really isn't any of her business where I am, but she still has a right to know.
Even though my business is my business, it's still not all about me. It's about Us. What do you guys think? I would try to be the kind of guy to not always nag her like that.
I'm sure it would be hard...but I wouldn't want to be that guy because she still has the freedom to do what she wants without people always nosing in her business, but if she wants to know what I was doing on my end I'll givein just for her if it makes her more comfortable.

Relationship arithmetic.

The question went loud and you agreed. 

Do you accept to get married and become one, to the will of the Almighty

Your response- yes I agree. 

From the time You walked down the aisle, you already agreed to the relationship arithmetic,

1+1=1.

So what does mean by saying it his/her business to know anything that concerns them directly- because she's you and his you too. 

The most important elements in every relationship are love, respect, mutual trust and effective communication. 

For your relationship to flourish you to communicate effectively with your significant other(S.O).

answering such question without hurting your relationship

Know that not every question is right to be answered for the sake of your relationship. When they ask to know, try at first to skip the question. 

Open up a new topic with unreferenced transition trying to avoid the question in the first place. 

If they are insistent to know where you are coming from, then just say it. 

Take a breath 

Cool your self

Remove every anger, rage or agitation. 

Hold their hands and just say

"I'm sorry for keeping you waiting, I was just coming from ......... 

If you must get this right, be sure to know that it's your spouse right to know and it's your service to your relationship to say it. 

A little thing can ruin your relationship, keep your mutual trust- be on top of small things. 

Share greater ways to answer such question without harming your relationship in the comment section, let the world learn from your experience.

It would just be great if you'd share this too.