I'm Queen of giving the silent treatment. Or as I like to think of it "I'll sit here and STFU while you run your mouth and look like a crazy ass fool"
You're not gonna promise to each other that you will no disappoint one another, because at some point you will. What is important is you don't go away, you don't escape, you don't leave one another just because you were disappointed. That's the meaning of fidelity.