If one of our Allies fucks around and finds out, we really shouldn't be obligated to back them,

You're not. You're not 'backing' your 'allies' because you're obligated to, but because you want to. Even NATO does not require a military response or any sort of response, if you actually read article 5. It's a promise of doing absolutely nothing.

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

States uphold their 'obligations' based on whether it is in their interests to do so. The most famous example being Italy refusing to join the Central Powers in 1914. Unfortunately, that is often the interests of the corrupt elites, not the people.