For clarity’s sake, my wife went through open heart surgery. She is the ‘B.’ The heart surgeon, as a result of the prognosis, surgery and recovery, put us both through great suffering. Clearly, his intent was to bring about a “greater good” for her, ‘B’ which would make it worth her suffering. However, being the empathetic person that I am, the entire episode caused great suffering to me, who would be your ‘A.’
Clearly, the surgeon would be no “idiot” even if he was to assert, “the suffering of ‘A’ will bring forth a greater good for ‘B’ and therefore it is WORTH it to inflict the suffering on ‘A’, so that ‘B’ would benefit from it - whether 'A” agrees or not".
Granted, the suffering of those who love others isn’t generally recognized as suffering, because most people, like you, only seem to recognize direct physical pain as suffering, but that isn’t true, is it?
If the surgeon was even half human, he would recognize – and not be an “idiot” for recognizing – that the empathetic suffering of a spouse ‘A’, for the greater good of the other spouse ‘B,’ would be worth inflicting the suffering on ‘A’ so that ‘B’ would benefit from it. Logically speaking ‘A’ would de facto be agreeing to it merely by suffering, because if s/he didn’t, the suffering wouldn’t even occur since absent any love for ‘B’, ‘A’ would not suffer in the first place.
Now you might claim, the doctor isn’t inflicting suffering on ‘A’ so that ‘B’ could benefit from it, but I think that it is in the nature of love that only by the empathetic suffering of ‘A’ would ‘B’ benefit from that suffering that results from empathy. A doctor wouldn’t be “an idiot” merely for recognizing that his actions are causing empathetic suffering to ‘A’ and thereby benefiting ‘B’ by bringing about that level of empathy. The risk would be that the doctor might not be certain that ‘A’ will, in fact, rise to the occasion or have any empathy at all. In that case, ‘A’ would not agree to being put through the suffering or would be too self-centered to suffer or care at all in the first place.
So it isn’t merely the worth of goods “in the eyes of the sufferer” that are the goods and suffering to be considered and balanced, unless your view is that all men are merely islands onto themselves where the worth of goods and suffering are concerned.
Now, you might respond that you included all sufferers, even empathetic ones, in your consideration, and that even ‘A’ benefits from 'B’s good fortune, but then you would be moving in the direction of admitting that your suffering calculus is far too inadequate to truly account for all benefits and all sufferers through all time in its results.