Decision-making for Profound Life Choices Isn't Much Like Decision-Making
There's a great article in the New Yorker about how life's biggest decisions seem to...just kind of happen. There's a short round-up of books and articles considering the paradox, some explaining it in terms of not knowing what the thing you want will actually be like, some by examining how aspiration is really meta-wanting (wanting to want something), and some by pointing out that our values and goals change over time in ways we could not have predicted ahead of time. On this last point I would superimpose a mechanism of biological imperatives; you don't decide to start wanting kids any more than you decide to get a carb craving.
I've noticed a similar experience with not having access to my own calculations, more for my decision to become a physician than to become a dad, although even with fatherhood, why now, here, with this person, is similarly hazy.
"...there is good and bad speculation, and this is not an unparalleled activity in science...Those scientists who have no taste for this sort of speculative enterprise will just have to stay in the trenches and do without it, while the rest of us risk embarrassing mistakes and have a lot of fun." - Dan Dennett