I saw an earlier post (maybe it inspired this ask, I don't know) where in one of the comments, someone accused Rochester of "lovebombing" by doing this.
Since then I've been pondering whether or not that accusation is fair.
"Lovebombing," if I understand it correctly, is a manipulation technique. It means purposefully showering a romantic partner with excessive affection, attention, and sometimes gifts to gain power over them.
Now we know that Rochester can be manipulative. There's the whole Blanche Ingram episode, the fortune teller disguise, and of course the methods he uses to hide his ultimate secret, Bertha. And Jane is uncomfortable with his attempts to shower her with expensive gifts and flattery, for all the reasons that lovebombing is uncomfortable. The flattery she feels is dishonest (she adores Rochester yet still admits he's not handsome, so why should he be suddenly calling her beautiful?), while the gifts make her too aware of the social difference between Rochester and herself and make her feel too much in Rochester's debt and power. When he describes his plan to give Jane a diamond necklace as putting a "chain round your neck," the wording was clearly intentional on Charlotte Brontë's part.
So the question is worth asking: is Rochester doing it on purpose? Is he trying to increase his power over Jane to try to ensure that she never leaves him, not even when she inevitably finds out about Bertha?
I'd like to think not. I prefer to think he's genuinely trying to give her love in the way he's been taught. Like the OP said, his marriage to Bertha was arranged, so he's never really courted a woman before. The only other women he's had relationships with were mistresses, who wanted him to spend money on them – for them, that was the whole purpose of being with him. Based on his past and on social expectations, Rochester assumes it will make Jane happy to have gowns and jewels lavished on her, and to be doted on and called a "beauty" and an "angel" for the first time in her life. After all, it made his mistresses happy and it would have made Blanche Ingram happy. He also wants to force other people to acknowledge Jane's worth and "beauty" by dressing her in the height of fashion, and to teach Jane to "value herself" too. When she resists, I assume that at first he thinks she's just being modest and self-doubting, which is why he won't stop.
(And now I'm thinking of the debate I've seen in the Wicked fandom about whether in the song "Popular," Glinda is doing the wrong thing by trying to give Elphaba a makeover that's isn't true to her character and is uncomfortable for her, or doing the right thing by helping Elphaba become more confident and more fashionable so that everyone will finally see her natural beauty. And I'm imagining Rochester singing a baritone rendition of "Popular" to Jane.)
I remember reading a post a long time ago which said something like "Jane and Rochester are both autistic, but Jane talks like an autistic person, while Rochester tries to talk like a neurotypical person." Of course that wasn't Brontë's intent, there was no concept of autism in her time. But there's truth in it. Jane and Rochester are a pair of eccentric misfits, which draws them together, but Rochester tries imperfectly to follow the rules of upper class society, while Jane, who's always been shut out from upper class society, makes no such effort.