there are, like, barely 2-3 scenes of them and you'll probably miss them if u dont pay close attention (i only noticed when i was reading for the second time) , but theres one in this:
https://www.mangago.zone/read-manga/no_you_na/
I don’t know any of that but this is the other way around, main is bl side is shoujo
https://www.mangago.zone/read-manga/faded_first_love/
Also you can try these maybe though I’m not sure if they’re like that https://www.mangago.zone/genre/Shounen%20Ai,Shoujo/?f=1&o=1&sortby=comment_count&e=
Any Shoujo manga/manhwa/manhua with a gay side couple (BL/GL)