It has to deal with society’s perception of dynamics. If two guys are silly-sweet they are adorable, if two girls are silly-sweet they have flowerbeds for brains. It has more to do with feminine and masculine identity in general. Not to mention rightfully the abuse and angst that comes from the expectations from many societies across the world about M/M. A lot of women are treated as commodities. Plus the fujoshi are fervent. Girls are also bigger CP fans. Girls like M/M and boys like W/W, and that’s because they can distance themselves form the character. There are those stereotypes of a supportive big sister, or a geek who is the anti-thesis to home wrecking. I made random notes, but if anything go out and find some good GL to enjoy. At first I was reluctant but then I basically ran out of any good BL, GL- I wouldn’t say they’re so different. But the dynamics and female ambition are unique to the development is societies perception. Fact is also, girls are allowed to be more vulnerable. The identity of being mentally sane in angst isn’t an option if there isn’t gunmetal available.
Now, I'm Ace af, but enjoy reading all sorts of romance. BL, BG, and GL. But I admittedly read a lot less GL. So, much of BL is actually just romance themed towards girls. If you slapped some boobs on the "bottom", as it were, it wouldn't be any different than BG romance. But because both are the romantic leads are male, the reader has a degree of separation between themselves and the MC who is their "replacement" in the story. If the MC doesn't fit their "ideal" female hero, that's ok, because it's a dude anyways. Some of the darker aspects of romance can be explored without the female reader feeling victimized through empathy because of this as well. (Which why there's an unfortunately large amount of rape in BL) There's also some power fantasy in there as well. Female CEOs just aren't as respected or plentiful in real life (or even in fiction). Or the leader of a demonic sect. Or a powerful general. Since they're both male, the reader can place themselves in either position. Males are also allowed to be more sexual in society. So our social conditioning finds BL sex scenes literally more acceptable than a sexually satisfied female MC for the simple fact that men are thought to be more sexual in general. A girl MC is all demure, "ieeee! yamete!". Males can be more, "F*** me!". Females, in all fiction and especially Asian fiction, usually get the short end of the stick, but at least in BL there's less females in general to feel for. GL just doesn't appeal as much as a romance to females unless they're Bi/Lesbian. Sure the female reader could put themself in either role, like BL, but what if you don't connect to either character? Or if you like one but hate the other romantic lead? And it's not like you're there for the boobs if you're straight. And for men, romance tends to be in the background behind plot action and sexual action (in general), so the hentai GL tends to be more popular to that crowd. They are definitely there for the boobs. Which just turns off most straight girls all together, cause then you have twice the number of females being sexually victimized. I'm not male though, so obviously these are just my opinions. Mileage may vary.
There are more fujoshi lol.. I think not a lot of people read GL.. Even guys doesnt read GL.. I think the Yuri tag on hentai are not that popular too compare to Yaoi. This is just my opinion, since I been reading BL as a female reader. Tho lately there are more GL manhwa and manhua coming out
Same sex relationships are extremely fetishized and for some reason media tends to EXTREMELY fetishize gay men. The only reason BL is more popular is because of societies views toward said thing. We view girl x girl as something thats "attractive" whilst we see something involving guy x guy as "forbidden". People tend to make a fetish out of things that are "forbidden".
Just as the comment by irregular person stated . It has to do with society. It is a common occurrence to see girls being quite friendly with one another but for guys to do that is very strange. ( Kinda how stuff like the no homo joke and the 5 or ten feet apart because we are not gay joke exist). I can remember watching a video where someone asked why people watched bl and a person said how " it felt forbidden!" And" the thrill it gave them to see men interact with one another like that". Believe it or not a lot of people do not watch bl because of the fact that they support the LGBTQIA+ community ( which is a whole thing in itself and also plays into why gl isnt that popular since some girls find the sight of others girls doing that disgusting or strange) . Additionally , on the fact of bl being mostly devoured by females. One of the things pointed out is the perception of the men. ( They are handsome, instead of plot you would see a lot of smut unless you search really deep). There are others reason that do exist but I'm not sure if the way I explain it would make sense / if I have or might drift away from what you asked.
For multiples reasons (sorry for my bad english, it's not my first language): 1. BL targets women. The authors are usually women and they write for women since it's their targeted public. GL is usually written by men for men. Since omen are usually more fervent and hardcore fans than men, there's no wonder why BL is popular. For instance, when you see a fandom that usually huge and popular, it is most likely because the target audience is women. There's thousands examples of that. Doja Cat, BTS, Haikyuu... Yes they have male fans, but the amount of females fans is incomparable. 2. Women love seeing M/M. They enjoy a world filled with only men in entertainment. Because it's usually more enjoyable. When a woman is portrayed in entertainment, she is usually a boring stereotypical that can't really stand for herself. And even if she did, she usually always hide behind a man's back at some point. She always shares some types of extreme weakness and vulnerability which does not fit with the perception that majority of women don't see themselves in today. Therefore, there ends up being no connection with those females characters and some are even portrayed as annoying, jealous and unable to control her emotions (men too, but people find it 50% endearing when they are jealous and possessive whereas for women 0%). Furthermore, women in entertainment are designed to please boys and not girls. With no attraction going on, few girls will be interested in GL. 3. For girls interested in men, who wouldn't like to watch or read something filled with handsome and cute men. It's like a feast to the eyes. So why not enjoy the ride and relax to such sight after a stressful day? 4. There's less GL content than BL. You can't really find good things (my opinion, maybe because I'm a girl, but ... actually no I don't think so. I'm pan therefore interested in girls, yet, I don't have the same thrill for GL as I do for BL.) There's many more reasons. I might add them later. Anyways, for anyone who wants here's some good GL manga/manhwa/manhua. Living Will What does the fox say? Warikitta Kankei Desukara Lily Sadistic Beauty Beloved by Jaeliu Pulse Bye Bye! Hope you enjoy the reading!
I agree that BL is written by women for women, but the majority of GL is actually written by lesbians for lesbians. This is really easy to tell for Chinese novels because there are entire webnovel sites for female readers, and this is where the GL novels can be found. As for why the disparity, lesbian readers gravitate strongly towards GL; much more so that female readers in general gravitate towards BL. But there are so many more of the latter that BL is going to dominate. That said, this still leaves us with a lot of GL novels out there and some of it is pretty high quality.