never in my life did i think i would be mounting a full-throated defence of an 1880s arranged marriage in 2025, but here we are, i guess. getting it out of the way: gladys has every right to be upset, scared, hesitant about her entire life changing; she gets to think her mother is the absolute worst for this, and take all the time she needs to adjust to her new life.
which she does! whereupon she realizes maybe her mother was right, and maybe she will actually be happy here, with hector, being in a position to manage an estate and forge her own path (crucially, with some distance from bertha — which like, most of us move out at some point and grow as people). i have enormous amounts of sympathy for her, and her walk down the aisle was heartbreaking to watch.
but: that doesn’t erase the fact that bertha was right. yes, gladys’ marriage is obviously socially advantageous for the entire russell family, bertha included, but it’s far and away the most advantageous thing for gladys herself.
bertha tells george as much, repeatedly. she is acutely aware how much her (and george's, by extension) social currency depends entirely on her own actions, and she cannot stop working on it for a minute, lest she jeopardize it. but her kids were born into far more privilege than she is, so in marrying off gladys, she cements gladys' status. no one will ever be able to question her presence in any room she enters, for the rest of her life. bertha has never had that, and she's doing her level best to make sure gladys does.
she'll be able to use her brain, too. we're seeing it already, with how gladys is growing into her own (with bertha's support and encouragement), running sidmouth, having input on the estate, etc. she'll have a staff to manage, charities to support, etc. plenty of things to do, and power to do them with.
now, hector. hector is a nice guy (raging royalist jfells would not have made this man the enemy). is it love at first sight? no. is he a sweet man who will let gladys live her life and support her in it? yep, and in a time where women had no legal autonomy and barely any bodily autonomy, that is worth its weight in gold. (if you think bertha didn't vet him beyond his bank account, i think you underestimate her, deeply.)
for george, all that mattered was that he loved bertha, which is why he can be so adamant about a love match (no matter that he betrays his own word by going along with the duke every. step. of. the. way. but that's a different problem.) but for any woman back then (and now, honestly), that could only be half of it. bertha loved him, yes, but he was safe (physically) and a way out and up. a calculated risk that paid off. and they both had the drive to make something of themselves.
gladys, for all her education and privilege, lacks that drive entirely. i don't think she could have painted a clear picture of what she wanted her future to be, and that opened her to the risk of running down the aisle toward the first nice boy she thought she'd fallen in love with, consequences absolutely be damned. bertha had the foresight (and life experience) to realize that would only come back to bite her, and steer her down a different path.
would she have had some social standing married to, say, billy carlton or archie baldwin? yeah. would it be guaranteed? nope. would she be afforded the same standard of living she's had for most of her life and grown accustomed to? probably not, considering both of those boys have the emotional backbones of wet blankets, running from the slightest challenge with their tails tucked between their legs. if either of them had been more mature/assertive/determined, i think they'd have had a much better shot. (we see bertha admire determination and pluck in marian!!)
but with the choices she had, hector was far and away the safest and most considered one. it's part luck that it ended as well as it did, but a bigger part of it, to me, is a considered calculation made by bertha — for her daughter's sake. and we know from the show that at the slightest sign of problems for gladys, she will move heaven and earth to fix them.
tl;dr: bertha russell knows what she's doing. let her cook. 💖