Domestic abuse and violence are frequent features not only in MC's life but also in some side characters. The struggle with suicidal thoughts and attempts happens in the side character's family.

How a side character finds out about their bodyswap at the right time and place, how a very short-term modeling contract (1yr) of MC to earn money for her part-time job with the no romantic relationship clause hinders her from confessing, it's has been ridiculously drawn out (booo, stalling!).

She is narrow-minded and primarily insecure because of how the love of her caregivers comes with a price tag.

It was always something she had to fight over. If they'd been more of a normal family, I doubt she'd been this rattled at MC's appearance in her life. She was far gone enough to be willing to sacrifice the rest of her life to marry someone for business relations and delude herself that she loves the douchebag they set her up with.
It's quite realistic and childlike of her to push all the blame on the seemingly easiest target, which I can give the novel props for until her cannon fodder role became too forceful.

I hated to see how she put elbow grease into whatever the parents expected her to achieve and accomplish, but just to get indirectly stomped all over and upstaged by the protagonist (School Score Ranking & Piano Competition Arc). She will be always a few steps behind the good guys, never failing or underperforming, but doomed to be overshadowed.

It is also unpleasant to see both author's narrative and others characters compare her to the real twin sister in looks, academics, and talents. Talents and academics aside, how the hell is she supposed to compete in appearances...?? She can't help how she was born as. (o*｡_｡) o
The narrative focuses more on the comparison in which of the sister's likeness is more fitting to be the brother's twin, but from time to time, it'll mention how her looks are indeed inferior to the MC's.

The parents are a lost case, so I won't bother going into details there since they're too self-absorbed and too classic 1-D villains.

Dad's power/fame/money hungry and has strong domestic abusive tendencies. His ego is so overblown, he would easily stomp anybody, including family, underneath him to be the sole one to triumph on the self-made pedestal.
It's easy to tell how strong and far his own insecurities and self-loathing go when he blows his top over having to grovel and brown-nose a more affluent family.

Mom's insecure and pathetic, partially because of her spouse, but hey, she made her own life decisions. Own it.
She chose and settled for a more comfortable lifestyle of suppression and submission than living as her own person.
She settled as being a housewife who's only good at spending money, whereas she could've chosen to pursue a career/hobby or attempt in building up social connections in the meantime.
After seeing parents like that, it's unsurprising for the cannon fodder to prioritize finances over family ties.

The sole ally didn't fall too far from the family tree either. Though somewhat caring and supportive of the main character, he turned his back on his cannon fodder sister real fast.
Instead of communicating or attempting to calm her down, he chose to temporarily run away through an exchange program and only return when things had long derailed. This is where he's similar to his own mother.

He chooses to blame his entire family for being disgusting, yet he's the one who'd turn a blind eye to most of the abuse going on in the family that turned his mother and cannon fodder sister partially like that. I'm not expecting or demanding much from a 16/17-year-old teenager.
Even if he didn't care for the other women living under his family's roof, he could've shown at least that he cared about the real twin sister, which he does.

It reflects again how similar he was to his mother in cowardly stepping back, wallowing in guilt, and giving themselves all kinds of excuses to not approach MC. At least he should've made the effort in approaching her and show some care, yet he didn't.

It didn't even mention him showing up at the hospital when she fainted from pain, which was widespread enough for her friend to rush over in a hurry instantly, but nope, didn't see a glimpse or a shadow of him. Sure, he might've been busy, but not even inquiring afterward? Yeesh.

The affection MC had for him should've been clear, in the short amount of time of them living together, she had given him, and only him, a gift.
When she left, out of all the gifts, it was his that she took with her (taking the water purifier and leaving the clothing like tailor-made dresses behind).
This should've been apparent if he'd only cared enough to bother.

"The blood of the covenant is thicker than the water of the womb."

The mother and brother sell the pathetic pity act to curry themselves into MC's life again, I personally, hated it.

More subtle signs of them being a**holes like the mother whining about her own incompetence and shortcomings, dropping one courtesy concern for MC, and doesn't inquire further how she's doing physically or if she's happy, etc. It's really obvious if you compare the main couple's mothers next to each other.
MC is the one who has to mother her own estranged mother while ML's mother is giving her real concern and love while also respecting her space, but wouldn't compromise when it comes to her wellbeing.

Brother basically emotionally blackmails MC to interact with the mother, overselling the mental state and indirectly pointing out she'd watch her mother kill herself if she didn't intervene and act chummy with them again by comparing their mother to the mother of his best friend who has already attempted su*cide by now (who has also pushed another son to su*cide with her antics and is on the brim of pushing her second son/bestie on his way to it too, ironic, if you think of this, can't help feel like the brother might be the worst one here).
The brother is prioritizing his own mother and himself over the sister if it means saving him some trouble from hearing the mother's whining which adds to his emotional baggage.
I see it as forcefully making her accept them with an underhanded method.
The victim doesn't have to compromise for the culprits' mistakes nor does she have to accept them because they put in minimum effort.
Frustratingly, this has also been canonically pointed out by the ML as well.
I can't help but see the worst in the Mu family (parents + brother). Either the perspective given was too little (mother + brother only, the father figure is obv. unrecyclable garbage) or what little was given is not nearly good enough to be worthy of forgiveness/love.
MC is still a teenager who'd like any normal human being yearning for family love, that's her weakness, and that's what Mu mom and brother are targeting.
Even if their gestures come from a good place, it doesn't change the fact that they mainly do it for their own peace of mind and of no true concern for their family member, which should be obvious if you'd simply look at it.

That's grossly overshadowed by the 'fluff' and as someone who is critically analyzing the family dynamics at this point, can't help but glare at it with concern.

in Chapter 187-188, he finally feels something for MC but it's only around Chapter 278 when they finally make their feelings clear... somewhat.

Her brother is also trying his best to make up with her.