Nobody likes to feel like they’ve been switched up on, especially by their boss. 

When you come to an agreement with someone, you probably hope that it will stand. You definitely hope that they don’t sell you out about it when things don’t go your way. That’s no way to treat someone. You also don’t want to be known as someone who will go back on their word and not hold true to the things you promised. Especially at work. If you want to collaborate with someone, you have to have some sort of exchange of trust. They trust you, you trust them, and you hope that this helps you reach your goals together. If there is no foundation of trust, then nothing is possible.