and in this particular case I felt like it fit what we'd been shown of the character and the relationship, rather than shoehorned in for narrative reasons

Oh yes, I should have said that, Watsonially it also made complete sense given both her character and the milieu around her (I mean, it's not exactly unrelated that her entire family is also keeping secrets from her and each other). And one of the reasons it irked me is that I definitely went through that period myself for much the same reasons, and it sucked, and so I kept wanting to be all "please fast forward ten years!"