I must say that if my 15 year old daughter hooked up with an 18 year old or if my 19 year old son started seeing a 15 or 16 year old girl I would be outraged! Which sounds like double standards and hypocritical but that's how I would feel.
i do wonder how Nowull would react if he discoversd 18 year old man was raping one of his daughters at the age of 12 or 13 - like in a few years, if Tillie impregnated by a grown man, in the way he abused Sue. would that be acceptable to him? totally okay, just as long as they later got married and had more children, no police involvement? i doubt it. yet equally, if one of his older sons brought home a child as their girlfriend, i doubt it would bother him. he'd probably be proud that his son was following hin his predatory footsteps, and reward him with his own bedroom.
and like you say, a 17 year old guy being attracted to a pre-pubescent 12/13 year old child is not comparable to a 15 year old dating an 18 year old. although that situation doesn't sit comfortably with me personally, but it's not as though you had a child at 15, and i very much doubt your now husband would have wanted to be in a relationship with you if you had been 12 at the time. and especially when you see the photos of Sue, even at the age of 14, she looked like a 10 year old little girl. she was likely still playing with dolls when Nowull started abusing her.