When we fail to set and maintain boundaries, we are being dishonest with people.

Let me explain.

A friend calls you at 10:00 PM to process their latest crisis with work, relationship, or what to do about the landscaping in the front yard. You've told this person before not to call after nine unless they need a ride to the Emergency Room. You're an early riser, and need to get your sleep.

But here they are again. Here's where you have a choice as to whether or not you respect them.

After learning that not ER rides are needed, you have a choice. You can ignore the boundary you set and talk as long as they want to to talk. You try not to sigh too loudly and are glad that they cannot see you roll your eyes.

If you do this, you've lied to her.  You've told her that you can listen and you can talk, and the truth is that you're doing neither. If you do this often enough you'll wind up ghosting them because you cannot say no any other way. Or you'll wind up exploding one night, completely trashing the relationship in the process. Neither one of which is respectful to the other person.

When we are clear and honest with other people, we show them respect. I'm sorry this is a tough time but I cannot talk right now. What about tomorrow? 

We don't say such things because we're afraid of coming off as being mean and uncaring. Ironically, if we ignore our own boundaries, sooner or later  we become exactly that because it's our only means of escape.

We don't say such things because we're afraid that the other person may become angry, and they may very well do that (especially if you have trained them that you will be endlessly available.) Then both of you have a choice as to what to do with that anger, which is another issue. If they choose to end the friendship over this, then they really weren't willing to have you as a friend but only a servant.

Respect the people in your life enough to tell them truth, whether it is a yes or a no.