I think its their upbringing showing itself.
Tiara grew up pampered by both her family and outsiders. She was the youngest and saw most prosperous times of her family. She was always the most beautiful girl in the society that every guy desires and thus her every word was given importance. Add to that her mother's social status and connections. This is also the reason she couldn't swallow the fact that her mother said she should put up with disrespect by her ex-fiance. She grew up confident and knows how to use things to her advantage, thus she simply left her family.
Kynell on the other hand grew up in shadows. His mom died soon after his birth. His father's existence is a big questionmark. His grandfather abhorred the fact that his daughter chose to have Kynell. Thus he put Kynell under a maid and didn't treat him as his daughter's legitimate child would have been treated. He grew up looking at things from afar that should have been available to him. He never got to voice his wants and desires. His lifestyle is very much a reflection of it all, he only has all that he needs. Nothing about his estate is fancy despite having earned enormous fortune. Nor does he know/recognize luxury and got duped into buying things that weren't worth all that much as luxury goods.
Tiara knows Kynell needs to speak up and tries to get that message across but Tiara has never had to adjust to someone else ever so she is a bit lacking too. They both suck at communication but are trying to make it work. It'll take some time for them to grasp each other's idiosyncrasies. I just hope nothing too big happens before that.
Ch. 51 on official chapters.
Me personally, I think she was doing too much. The MC demanded the ML to apologize for assuming that she thought his scars were hideous. She could've at least sympathized with him instead of doing all that. Like, if she had demanded an apology and explained why she was angry, and let him apologize, then that would have been better. Maybe console him a bit and reassure him that his scars aren't a problem.
And then him sending all that gold and jewels to her was his way of apologizing, but she didn't understand that and told them to throw it all away?? Like girly, there's people starving on the streets and you're gonna throw that all away 'cause you're mad at him??? It wasn't even a valid reason to get mad either, she's just letting her husband think he's in the wrong for being insecure.
I understand that she doesn't understand how he could be insecure, but it's the little things that hurt people. Also, the ML needs to start speaking up 'cause he's so whipped for her that he's letting her walk all over him. I'm NOT saying he should take away her freedom and actlike an asshole, but these little instances where she gets super mad over small things like this and then takes out her anger by giving the silent treatment when she should be explaining how she feels and clear up the misunderstanding really gets on my nerves.
Still love her tho, she's so fucking cool and their relationship is cute. They have their flaws though :/