An excellent example of failure to adhere to and practice the Golden Rule is setting false expectations in the minds of others.
Nobody pitches a perfect game. We all mess this up, some a lot more than others.
If you have the power to set someone's expectations, be responsible about it.
That person uses their expectations to plan their scarce time and if you've provided them with false expectations, you're attacking their ability to effectively live their life.
Don't take this responsibility lightly.
Furthermore, if your victim points out your shortcoming in that regard, check your ego, eat your crow, apologize, and try not to do it again. Be better.