Hey Butterfly! So I have a personal headcanon that, unlike Robb who was more of a baby born of duty (i.e. Ned and Cat's duty to one another on the night of their marriage), Sansa was the first Stark child to be born of love. This is also why I think there is a three year age gap between Robb and Sansa, enough time for Ned and Cat to begin to warm up to each other in Winterfell. Would you say I'm reading too much into it (probably am) and/or is it semi plausible? Thanks! :)
Well, it’s not a bad idea, but the age gap between Robb and Sansa really isn’t that big, especially when compared to all of Ned and Cat’s kids. I mean, it’s 3-2-2-4, and that general 2-year spacing also looks fairly natural for a breastfeeding woman, with the extra year between Robb and Sansa probably due to the war and Ned’s later return from Dorne and so on. (BTW, I don’t think anyone suggests Ned and Cat had a falling out between Bran and Rickon, but something unfortunate might have happened there.)
That said, it is probable that Ned and Cat did come to fall in love and treat sex as more than just a duty before the birth of most of their children. The first could have been Sansa, but it may as well have been Arya or even Bran. (Recall how Cat considers Bran the most loving and sweetest of all her children.) But still, it doesn’t need to have taken so long, so yes, I agree that it’s at least semi-plausible that in the time after Ned’s return to Winterfell, after his and Cat’s initial uncertainty and stiffness (re the trouble with Jon, and him frightening her re Ashara Dayne etc), that he did come to court her and such, so that by early 286AC when Sansa was conceived, they were “making love”. After all, Cat’s narration does tell us:
And after the war, at Winterfell, I had love enough for any woman, once I found the good sweet heart beneath Ned’s solemn face.
–ASOS, Catelyn V
But y’know, you really don’t need me to justify your headcanons, especially in regard to something we’ll almost certainly never see in actual canon. :( Though if you’re interested, I know there are lots of Ned/Cat fanfics on the subject of how their marriage of duty became one of love. It’s probably a good percentage of them, really. I even vaguely recall a short drabble-like fic that connected the mood of each conception with the personality of the resulting child (though I read it on tumblr back in 2011 and I haven’t been able to find it since, and not on LJ or AO3 or FF.net either, oh well), and it had all hearts & flowers & romance connected to Sansa’s song-loving romantic personality… So what I’m saying is, you’re definitely not alone in your headcanon, either way. :)