All actions are equally trivial for a deity because they are supremely powerful. The only thing a deity cannot do is the logically impossible. Since typically a deity is also the creator that makes them responsible for every single event that occurs. That is what being a deity means, to be able to do anything short of create rocks they cant lift or destroy themselves.
"Once again, experience belies this."
You are not a deity, you are not supremely powerful. You can therefore be benevolent within the bounds of what you are able to do. No logical contradiction is implied if you don't do the absolute maximal amount of good.
Further you can be benevolent some of the time and not benevolent at other time, your benevolence can change through time. A deity is a timeless entity, a single instance of lacking in benevolence means the deity is not benevolent because a deities actions cannot be thought of as temporally localised.
You cannot take examples of what is possible and impossible for you and apply it to a deity, it just does not work. If you want to claim a benevolent deity exists you have to show it is reasonable such a concept is not self contradictory working from the definition itself, not from your experiences because you are a very different entity from that deity. You could punch someone in the mouth for no reason (or even for fun and profit), a benevolent deity cannot because it implies a logical contradiction.
It isn't that the deity has an obligation. It is that it is logically contradictory for a benevolent deity to act in an evil manner or fail to act in a good one. A benevolent deity isn't obliged to do good, it is logically contradictory for them to fail to.
"The deity, however, is bound to a singular course of action, predetermined by myself, my wife, and the other party."
Yes exactly. But they are not bound by moral obligation, they are bound by the requirement that their own nature be internally consistent. The only way around this is to argue that gods notion of benevolence is so alien to our own that rape, torture, death and genocide somehow working for the greater good can be considered benevolence.
Free will is a self contradictory concept whoever it is applied to but in this case that has precisely zero impact. A benevolent deity can only chose between the maximally good actions (or inactions) available to it, not because it lacks free will (however you define it), and not because it experiences a moral obligation, but for the same reason it cannot create square circles. You cant choose to be a married bachelor and a benevolent deity cant choose to fail to do good or to do evil.