Emotional Promise - This is a promise that is created when emotional but can be voided if that emotion isn't felt when the promise is needed for follow through.
Logical Promise - This is a promise created in any circumstance that the person promising it, intends to follow through regardless of how they feel when they need to follow through with it.
Man asks woman to marry her. Woman says yes. They go get married and vow to be faithful to each other and live for each other for the rest of their days.
Now later on the man / woman is feeling down and doesn't feel loved anymore so they decide to cheat.
The promise of staying faithful is voided due to an emotional promise being used and not a logical promise being used.
Emotional promises are a bad thing. Always. Do not promise something that is voided when you no longer are feeling it emotionally. If you make a promise, follow through with it. If you are feeling down in a relationship, you don't cheat, you talk to your partner. If they don't want to change, then you still don't cheat. You leave the situation or tell them you are going to go find what you are missing. You don't lie, cheat, decieve, etc. You be upfront and use logical promises.
Never use emotional promises or do something against your promises just because of emotion.