Or you can trust the wisdom of the Bible.
You get your neighbor's wife pregnant. Despite your best intentions you start seeing the child as your's and begin showing an undesired interest in his upbringing. Meanwhile, the husband starts seeing the child as more your's also. Resentments bubble to the surface, domestic turmoil ensues and the marriage breaks up.
Unfortunately, you don't want to marry the wife -- it wasn't part of the arragnement -- and she ends up raising your son in poverty.
The future I describe is much more likely based on the record of the human experience than the happy-ever-after scene you imply will occur.
My scenario has a long and proud history. And according to my informal survey, otherwise sound marriages are at least as likely to break up for lack of deperately desired issue, as for other reasons. If you have actual statistics to offer me, rather than highly unlikely bs scenarios that ascribe female emotions to males, by all means offer them up. Until then, I'll assume that you are still trying to wriggle off the hook by insisting that the posed dilemma isn't about adult humans with adult forsight about adult problems, when, in fact, it is.
Well, actually, I did trust in the bible, which says, "love thy neighbor as thyself", and "do unto others as you would have them do unto you". No where do I see the commandment "assume your neighbors are like erring children whose concerns we can therefore discount in a loving relationship."
Is this sort of like the flavor of agape love we discussed earlier with exmarine? Which permits enslavement and slaughter provided it it done out of love?