Okay, first off I should note that boy monkeys and puppies break many a contract themselves due to immaturity. Even cows and St.Bernards break contracts for reasons like "I can't let the baby cry in the crib even though I know I should." Really what the cow/St. Bernard are usually guilty of is letting their partner out of the contract due to excessive sensibility.
A contract isn't a contract unless it is enforceable. Therefore, I think much of what you are saying is true. However, I think you may be confusing the lionesses inability to honor a contract with her refusal to exactly sign a contract to begin with. Lions do this too. As in "I wish you would remember to take out the trash."..."Yeah, okay, whatever, I'm watching the game. Quit blocking the screen." Has a contract been made in this instance? Will the lion get grumpy if he hears "You said you would remember to take out the trash!" the following week? Will he feel a sense of shame for violating a sacred contract made with his word which is his honor?
When you reveal yourself as vulnerable in regards to a contract, you let your partner know how valuable it is to you. It's really just the opposite side of the same coin by which you let your partner know its value by strongly enforcing the contract. For instance, consider the difference between stating to a woman "I will leave you if you cheat on me." and stating "I will leave you if you cheat on me because I care very deeply about fidelity." or simply stating "I care very deeply about fidelity.". If the woman replies "I understand." she hasn't made a contract but she will feel more like she has done you wrong because of the latter statement rather than the former. If a woman says "I will not cheat on you because I understand that you care deeply about fidelity." it is quite possibly a better contract than if she says "I will not cheat on you because I understand that you will leave me if I do." because the cow is a better co-signer on a contract than the bunny.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver