One comment: taken literally, this description
(note: I use the phrase "net happiness" to mean the sum of all happiness in the future minus the sum of all suffering in the future)
completely eliminates second-order effects (and I answered accordingly). However, I suspect many people will consider second-order effects anyway. If something is sufficiently strange, I think explicitly stating it, even in unambiguous language, it is often not enough; you have to make it super-extra clear.
Agreed. Take the unhappy pregnant parent raising the hypothetically future happy child - unfortunately I just couldn't decouple this.
As an unhappy parent, my unhappiness gets transmitted to my children, and their unhappiness feeds back to me in a negative feedback loop. We're all unhappy. (And, indeed, the literature on postpartum depression and its resultant effects on children are quite clear on this as well - it's not just my personal experience.)
My rationalisation of this is that I'm a negative utilitarian and I'm not a longtermist - I don't think the future child's theoretical happiness can outweigh the the mother's present unhappiness.
But in actuality I think it's probably a decoupling issue.
It looks like a very specific form of utilitarianism: something like linear state sum hedonic utilitarianism.
I created a mega thread of philosophy polls to help you find out how utilitarian you are:
https://twitter.com/SpencrGreenberg/status/1568595511522852871
It includes thought experiments related to: