Although I don’t have a brother in the parsha myself, I spoke to a friend of mine whose 24-year-old brother was in shidduchim for the last year. She told me that her mother had a stack of resumes ad hashamayim, and every few days she’d look into another girl. She could kind of decide to say no for any random reason, until she found the “perfect” girl.
This kind of mentality is the reason that so much of what is wrong with shidduchim is blamed on the boy’s mother.
Another thing is that often boys’ mothers are looking for things in their daughters-in-law that their sons could not care less about- i.e. G.O. in high school (boys have no clue what G.O. is!), dresses in style (many boys don’t care, though some do), “bubbly/spunky”, etc. I’m not saying that this doesn’t work the other way, too, but it tends to run this way more often.
In general, the attitude of “my son has everything coming to him because he’s a top learner” (whatever a top learner means) seems to come from boys’ mothers. I’ve heard it directly from mothers and from shadchanim about the mothers.
Again, I’m not saying there aren’t others to blame- just that boys’ mothers have a lot to do with it.