"Is there something unique, which she needs, that only I can give d16, as opposed to W and her (someday) boyfriend(s)? "
YES!! you are her FATHER!! you are a major role model in her life. YOU will provide her with the model of her future husband by providing either good or bad examples. Your job is to teach her what is expected from her future male relationships, how she should be treated, how she should treat them.
for kids, a mother is the role model for how a woman should treat her husband. and the father is the role model for how a husband should treat his wife.
Luke, to me, this talk of giving your d16 space, or moving to the US for work, strikes me as a method of running from your problems. really take a good look at why you're trying to find reasons/excuses to leave.
yes, life would be much easier if we could just walk away from the mess and start new. and many people do this. but that doesnt make it right.
"In a ham and eggs breakfast, the hen is involved, but the pig is committed".
