Love Live was announced in and ran its fan voting from the earliest days through Dengeki G's. The magazine is primarily (though not exclusively) targeted towards adult males (or at least older teens). It absolutely was never a children-targeted franchise like Aikatsu. It has developed a good-sized female fanbase, though, and yes, even more so in the west, where its fandom is fairly even.
And these two were shipped because their interaction in the Code Of Brawl event was absolutely interesting,followed by tit bits dropped in both Exusiais' and Mostimas' extra trust stories.
With the translation we've been getting from CN,the flood gates have swung open.