It doesn't interfere in future quests that involves them?
Meh! there is nothing stopping you from building their affection again if you need too. Vamp potions can make that pretty easy. Mostly I just visit the ones that I care about and ignore the others unless there is new content I'm trying to unlock.
And if all else fails you can cheat
There is a built in cheat that stops the affection decay (or maybe reduces it... I forget, I never use it)
#41,339
I tend to use a save editor but using the built in option instead greatly reduces the chances that you will screw up your save.
Edit: even if it did interfere with future quests, it would still interfere less than not getting them pregnant to begin with like you were talking about
#41,435