http://www.mangago.zone/read-manga/hanayome_wa_juunanasai/
Don’t think this is it but it’s still worthwhile :)
At the description I thought of the same story.
Could it perhaps be this one? :)
http://www.mangago.zone/read-manga/boku_no_ano_ko/
It’s not this one but now I got a new book to read during this quarantine!
Yes it’s this one thank you very much!!!
So I read this manga a long tome ago it was about these two dudes who were arranged to marry but one of the dudes thought his fiancé was a girl (his mom forgot to mention it was a dude) and was disappointed to find it was a guy. Also I think the moms were friends and the protagonist had a little sister