“He does have pretty hair. If the gods are good and he lives long enough to wed, his wife will admire his hair, surely. That much she will love about him.”
And this is just so Sansa, she always sees the best in people. Ironically this is also what makes her an unreliable narrator, as GRRM has pointed out. She twists events in order to keep living through all the horrible events she’s seen. In this case though I think it might also show how Littlefinger’s thinking is becoming a part of her own. Fool, because he is still young and naïve as to how things work. It’s how Littlefinger thinks of people, and now Littlefinger’s influence has worked its way into her. But the good thing is that we actively see her fighting it by suddenly complementing his good features.
Later throughout the chapter we do see a slightly more manipulative version of Sansa, although I think it’s more leaning towards sass and I’m all here for it tbh, but we also see her thinking a lot about Winterfell and her family. Ned was mentioned, Robb was, Jeyne was, Winterfell was, I mean even though this was chapter was titled Alayne, there is so much Sansa in it.