If things had gone better in canon and Catelyn had survived and been reunited with Arya, or maybe your Love and Honour was canon, how do you think Catelyn would have felt about Arya's short positive relationship with Lady Smallwood? I feel she'd have been very happy someone helped Arya but maybe be a tiny bit jealous, like she sort of was with Osha over Rickon, about it too especially if Arya tells her about the dress and needle work and being called pretty without any real context on it all.
Well, Catelyn’s initial jealousy of Osha in Love and Honor, (which she knows is terribly unfair from the very beginning and tries hard to get past), is based on SEEING her with her son, and watching Rickon choose to stay with Osha and reject her as a stranger when they are first reunited. That hurt her deely, and she honestly wondered if Rickon would ever truly remember her, much less love her as a mother again. Hence, the jealousy. That’s a completely different situation from
I think if Arya told her mother the entire story of her brief stay with Lady Smallwood in the world of Love and Honor, she’d first of all feel gratitude for the woman’s care for her. Nothing is more important to Catelyn than the well-being of her children. The entire time they were separated, she was praying for their health and safety and didn’t want them frightened or lonely or hurt. While she could not be with them, she’d have been happy to have them protected from any of those things by anyone who had there best welfare at heart. She isn’t selfish enough to feel that she alone must provide that.
As for how she’d have felt about the specifics of that stay: She’d have smiled and shaken her head in recognition of the little girl who’d been rather put out at being bathed and put in a dress not once, but TWICE–but would have realized that having someone take that kind of care of her HAD comforted Arya in some ways, even if the child wasn’t about to admit it even to herself. She’d have been amused by Arya’s answering Lady Smallwood truthfully enough that she enjoyed “needlework”–allowing the lady to be pleased with her answer without explaining the entire truth of it. She would have laughed (while trying to look mildly disapproving) about Arya getting filthy and tearing one of the dresses in short order, remembering the little girl who was often mistaken for a stable boy at Winterfell. If Arya then told her about how Lady Smallwood gave her her dead son’s breeches and tunic and jerkin to wear when she rode out and how that made her feel sad for her and ashamed of how she’d behaved in tearing the acorn dress, Catelyn’s heart would have wanted to reach out to hold the little girl she remembered so well who couldn’t behave like a lady to save her life, but never truly meant to hurt anyone (except maybe Sansa at times when she was angry with her) and was genuinely sorry if she did. And finally, when Arya told her that Lady Smallwood responded to her apology by simply telling her she was pretty, Catelyn would have been able to see what that meant to her daughter and would have regretted not saying it herself more clearly and without qualifications when Arya was child in Winterfell.
But while her recognition that Lady Smallwood’s simple compliment had offered Arya a type of reassurance that she hadn’t received enough of from her own mother might cause Catelyn some sadness and regret regarding her own actions, I don’t believe she’d feel any real jealousy toward Lady Smallwood. Her daughter survived; she’s back safe in Winterfell with her family; Catelyn and Arya (and all the surviving Starks) are working to move forward past all their hurts, and Lady Smallwood is simply someone who gave her child some comfort when she wasn’t present to do so herself. And for that, she would be immensely grateful.
I wrote this response using the Love and Honor universe because it’s the canon divergence in which Arya’s encounter with Lady Smallwood would have occurred precisely as it does in the books and in which Catelyn and Arya both survive to return to Winterfell that I know in detail (for obvious reasons, LOL!)
Her precise emotions in other scenarios might vary depending upon what experiences she and Arya had both had prior to their reunion, but I honestly can’t imagine a scenario where jealousy would be significant part of the equation. Catelyn is certainly capable of jealousy, but she doesn’t tend to hold onto jealousy over situations that have no current impact on her. (For instance, if Arya talked frequently about how wonderful Lady Smallwood had been, she might become somewhat envious–worried that her daughter preferred the woman to her–just as her jealousy Jon Snow’s mother was kept alive only by Ned’s obvious love for Jon and his steadfast refusal to tell his wife a thing about the woman he had apparently loved so deeply.)
Oh, and if she ever heard about Arya’s indignation about Lady Smallwood discussing with the men the rumors about Lady Catelyn Stark freeing the Kingslayer, she would have been deeply touched by her daughter’s unwavering loyalty. But she’d never hear that part, because no way would Arya Stark tell her mother something that would insult or hurt her. :-)