When I get a business loan from a bank, I make no promise to pay it back. I promise to pay it back with interest if the business succeeds, and we agree that it might not succeed and they might lose their principal.
When I tell my romantic partner that I won't sleep with other people, it's an absolute promise.
Infidelity happens. So do divorces. Also, people get sick. People die. Society has procedures for these things.
There are very few absolute promises. Most contracts have some provision for what happens when they're broken. If there isn't one, it's poorly written.
When I get a business loan from a bank, I make no promise to pay it back. I promise to pay it back with interest if the business succeeds, and we agree that it might not succeed and they might lose their principal.
When I tell my romantic partner that I won't sleep with other people, it's an absolute promise.