it's shounen Ai...there won't be any new girl or anything like that coming between them lol. So definitely not Shoujo!! Yeci
Well shojo doesn't necessarily mean that it's the relationship between boy x girl but more like something young girls would like that's why it's sometimes confused as romance between hetero couples
shoujo just means it's target audience is younger women and girls. shounen-ai means it has fluffy love between guys. the manga can have both tags because BL is mostly targeted at women anyway.
It's shoujo I thought it's shounen ai... Why