What more is there to life than a fairy tale happily ever after? Wait, don't answer that. First, take a moment to consider how many options there were for early-20th-century British women aside from getting married young, often to men they hated. Right. Now…
Already married at twenty-three, Mrs. Morel loves her husband. At first, anyway. That's because he's so different from the men she's used to meeting at her parents' parties. She's blown away by his zest for life.
You can see her admiration for him in their early flirting:
She watched him. He danced well, as if it were natural and joyous in him to dance […] Her father was to her the type of all men. And George Coppard, proud in his bearing […] was very different from the miner. (1.82)
As the novel tells us, Mrs. Morel is a person with big ideas:
What she liked most of all was an argument on religion or philosophy or politics with some educated man. This she did not often enjoy. So she always had people tell her about themselves, finding her pleasure so. (1.80)
In other words, Mrs. Morel so rarely finds an outlet for her ideas that she prefers to go to parties to observe human behavior instead. When she meets Walter, she thinks he's the most interesting man he's ever met, and she hopes he'll sate her philosophizin' desires.
Unfortunately, though, Walter Morel quickly goes from Grade A Husband Material to Grade A Alcoholic Who Abuses His Family (there were a lot of "a"s in there, weren't there? We're so smart.) We also learn that he lied to Gertrude about how much money he had going into the marriage.
Now Mrs. Morel might not come from a rich family. But she comes from a family that used to be rich, so she's a very well educated, and rather proud, woman. She basically considers herself a grand, well-to-do lady trapped in a crummy life. (Delusions of grandeur, much?)
Anyway, it's clear that she ends up totally hating her poor life with her poor miner husband, and her marriage to Walter turns her bitter:
She was sick of it, the struggle with poverty and ugliness and meanness. (1.44)
Gertrude was hoping to never have to deal with such hardships. And all of her dreams for a grand philosophical life ended when she got hitched to Walter.
As time goes on, Walter becomes very abusive to Gertrude, and she steels herself against him. She used to be so deep. But now she only cares about frivolous things and being way, super over-invested in her children's lives; she lost her sense of self by marrying a man who wants nothing to do with challenging ideas.
D.H. Lawrence even shows us how deeply she loses her identity in her marriage by the way he never calls her by her first name after she marries Walter. From that point, she's only Mrs. Morel. Get it? Her defining characteristic has become her bad marriage to Walter.
Since it's obvious to everyone (though, stunningly, sometimes unclear to Mrs. Morel because she can be kind of emotionally dense now) that her marriage cannot be saved, puts all of her love into her children:
His wife was casting him off, half-regretfully, but relentlessly; casting him off and turning now for love and life to the children. (3.16)
But here's the problem: Mrs. Morel hasn't forgotten about all the ambitions she had before marrying Walter. She wants to use her children as a sort of reset button for her own life. Huh? What's that?
Yes, you're right: this family dynamic is an absolute setup for total disaster.
Our ole narrator does not stop talking about how Mrs. Morel invests her ruined hopes and dreams in her children, especially William and Paul. So we guess this notion is pretty important in Sons and Lovers. Anywho, specifically, Mrs. Morel wants William and Paul to go out into the business world and do great things in her name:
Now she had two sons in the world […] [and] these men would work out what she wanted; they were derived from her, they were of her, and their works would also be hers. (5.236)
For starters, she wants her sons to conquer the world in ways she never could because:
This second reason is no doubt why she invests her failed life dreams in her eldest sons instead of her daughter, Annie.
In short, Mrs. Morel considers her children to be extensions of herself. Any achievements they might have are, in her mind, her own accomplishments. All in all, she has a really haughty approach to her children, finding in them an outlet for the pride she likes to feel around others: "She walked on, as proud a little woman as any in Nottingham […] All [Paul's] work was hers" (8.104).
We kind of wish the term Helicopter Parenting were around in Mrs. Morel's time. Might have given the old lady some clarity.
But it wasn't, and Mrs. Morel never gets hip to how overbearing she is. Most importantly to the plot of the novel, she's always standing in the way of her sons' love lives. And, after William dies, she really needs Paul to be hers, and hers alone… though she might not ever admit this to herself on a conscious level.
So the woman's none to happy when Paul starts shacking up with Miriam. She makes remarks like:
[Miriam's] not like an ordinary woman, who can leave me my share in [Paul]. She wants to absorb him. She wants to draw him out and absorb him till there is nothing left of him, even for himself. (8.236)
Clearly, what's going on is that she doesn't want Paul to love any woman but his mother. So it's ironic that Mrs. Morel finds Miriam too clingy as a lover, because the reality is that this is exactly what Mrs. Morel herself is like in her relationship with Paul. She's just projecting her own problems onto Miriam, and hating the girl for it.
As Mrs. Morel gets sicker and sicker from her giant tummy tumor, we learn a completely new thing about her: she's a fighter. At least when it comes to refusing to die, anyway. For some reasons we have trouble understanding, especially given that she hates her life so much, Mrs. Morel suffers terrible pain for the sake of simply staying alive:
[Death] was coming, she knew. She had to submit to it. But she would never entreat it or make friends with it. Blind, with her face hut hard and blind, she was pushed toward the door. The days passed, the weeks, the months. (14.151)
We suppose that, even when facing death, Mrs. Morel is just a really clingy woman. This clinginess comes out most strongly in her final moments, as she takes an agonizing amount of time to die
The great snoring sound began again—there was a painful pause while the breath was held—back came the rasping breath. (14.296)
All in all, Mrs. Morel isn't the type to give into anything, whether it's death or her son's girlfriends. She's very stubborn about almost every aspect of her life, which helps explain why she won't let go of her dreams just because she married the wrong guy.
But it's not like she has the gall to go after what she wants herself (though, admittedly, that would've been tough as a poor woman in her day and age). Mrs. Morel just channels all of her aspirations into her sons, thereby impeding their personal development forever. As the old adage goes: when in doubt, blame your mother.