Kyouko feels like a pretty realistic depiction of a certain type of person.
Of course some people are more gifted in natural looks/beauty than others, and that's certainly a big factor in catching the eye of potential romantic partners. However, even though Rei was obviously being a smug asshole about the way that he said his piece, he did at least have a point. If you're desperately trying to "entice a man", as he put it, there is some onus on you to put some effort into presenting yourself as well as you can. You want to put your best foot forward and do whatever you can to make yourself appealing looks- and personality-wise to the person you're interested in, because they don't have any obligation to force themselves to try to get to know you and fall in love with your "inner beauty".
Kyouko claims that she's always been self-conscious about her appearance and that she was jealous of her friends, yet her friends are clearly not the type to try and use Kyouko as the "ugly girl" in their friend group or anything like that. They would surely have given her advice on hairstyles, fashion, or anything else if she ever asked, but she seemingly never did. Not only was she not at all interested in improving that part of herself, she clearly has a very dismissive view of her friends when it comes to that stuff. On top of that, she has been shown to have a pretty polarizing personality, where she just starts one-sidedly yapping about health foods, her favorite bands, or other interests whenever she has an opportunity, often in a pretty condescending way.
It's pretty telling that she just thinks of Mahoro as "carefree", somehow landing an attractive husband without any real effort, when it's clear that Mahoro puts a lot of work into maintaining her appearance, doing her best at cooking and cleaning, and being a good friend and decent human being, among other things. The same is (seemingly) true for Rio and Momoka as well, but Kyouko dismisses all of it as just being the gap between her and them in their natural beauty. She doesn't seem to have any self-awareness of that difference in effort between her and her friends, and has this borderline incel way of thinking, blaming everything on guys only liking the pretty girls, essentially going "I've tried nothing and I'm all out of ideas".
If someone puts in an honest effort to really improve themselves and yet still struggles to find a romantic partner that they're happy with, then they definitely deserve to be consoled. Sometimes life just isn't fair. But in Kyouko's case, the moment a man seemed even remotely receptive to talking to her about her interests, she immediately got full of herself and felt that she could just steal him away from his wife solely through entertaining them with conversation about that shared interest. She was even willing to betray a longtime friend to do so, and even spoke poorly of her behind her back to try and win the husband over, showing that natural beauty is far from the only aspect she is lacking in as a person.