Not being able to take in, process, and remember new information that does not line up with what's already in their head is one of the cognitive issues that can be seen in humans in general, but is markedly apparent in certain disorders and illnesses, especially with Narcissism.
If their "story" has Stella cast in character as being a person who has little or no experience in something, then they will just keep "writing" her that way, no matter what they see or hear that indicates differently.
If they've cast Stella as (if they think of her as) physically weak and fragile, then when they SEE her landscaping her property, or building a porch onto her house, they CAN'T accept the new information and "rewrite" their character of Stella, because they can't handle the contradictory information.
They can't think "Oh, I was quite wrong in my assumptions about Stella, I should not have judged her like that, I was not right or correct." Because the REASON they thought of Stella as weak and fragile was about THEIR OWN identity and insecurity issues. It had nothing to do with Stella, or with reality.
Making Stella weak allowed them to feel STRONG in comparison to her: "I might not be the Hulk, or even the strongest person in my family, but there's a person that I'm stronger than."
Instead, they will try to delete the new information, or try to rationalize HOW "weak, fragile Stella" is able to do this "difficult" work. Their ensuing behaviors as a result of their attempts at deleting, denying, and rationalizing may include:
~ Avoid Stella, and avoid seeing her do these things
~ Treat Stella like she must be horribly exhausted and overtaxed, and "out of her depth"
~ Try to take over Stella's projects
~ Criticize and "critique" everything Stella is doing or has done
~ Keep trying to "advise" Stella, as if she knows much less about these things than they do
~ Talk about Stella behind her back, implying that she's grandiose or unstable (she's not following the "character" they wrote for her, so she must be crazy or bad)
Often they will find some "reason" that they don't LIKE HER anymore, so they'll have an excuse not to be around her very much. A person with Narcissism may have a tantrum and wildly reject Stella, creating a new story in their heads about Stella being a terrible person, so they can give themselves (and others) an excuse about tearing her down and rejecting her.
People with Narcissism issues feel emotional pain when someone in their cast of characters shows that they are not the person they were "written" as, because it's a blow to their already wounded and weakened ego identity (boundaries). A person who is "supposed to be" someone who is LESSER than the N. is supposed to ACT that way, or they're WRECKING the N's world, where the N. uses them to compare themselves to.
If they're not lesser, weaker, less capable, less intelligent, less "worthy" than the N., then they are ruining the N's SELF-IMAGE.
The average Narcissist's self-image, identity, and self-worth is based on how they COMPARE to OTHER PEOPLE.
Without other people to compare themselves to, they don't know who or what they ARE. They NEED others to be either someone who is greater than them so they can follow them, OR someone who is lesser than them so they can feel like they're MORE than that person. Narcissists DO NOT want these "characters" to change, because they are basing their identity and worth on who and what they are in comparison to others.
They NEED to have HEROES, "important people" with titles, power, and prestige to be in the world, so that they can keep their imagined "Hierarchy" alive. (Mostly people they don't know personally). They'll often refer to these "important people" as if they are above other human beings and therefore smarter, better, more capable, more WORTHY, more everything, and especially "above" targets whom they're trying to diminish.
AND they NEED to have people in their lives whom they have cast as "inferiors" in whatever way they can come up with, because that's the only way they can feel like they have worth or value as a person.
It's all a construct of the imagination.
There are, however, sociopathic Narcissists who are quite aware that these "Hierarchies" that people create are not real, but they perpetuate them and encourage them purposely in order to USE them for manipulation purposes. A good example of that is the SCAMS on the internet, the "Catfish" who have been exposed on some talk shows, scamming people out of thousands of dollars. Also the SCAMS on Craigslist out of other countries, such as the fake ads for home rentals. These are sociopathic Narcissists using people's own beliefs in hierarchy to manipulate them.
They're also common on dating sites, and on other social media.