Especially when it concerns a person's private life. Every person needs to have privacy about his or her own decisions in life. But, every choice we make, even a private one, is going to affect other people through the actions we take to carry out our decisions.
Every action has a reaction.
And everything we do is going to affect someone else. Everyone eats, breathes, moves around doing daily tasks, etc. In this we are all the same. Humans are equal and should expect to be treated with respect and at the same time respectfully allow everyone else to have equal rights as well. We need to respect other people from the get-go if we expect respect from others around us.