To be fair, Riot does have to toe the line with things not considered universally "welcome" as BS as some of us find it.
I mean, Graves can't even have a cigar. We're highly unlikely to see Caitlyn and Vi's glorious wedding with Diana and Leona catching the flowers afterwards the romance we're all waiting for.
Champions have been implied to swing the other way from time to time (or maybe we players just read into it too much!). Maybe some Rioter wanted a kiss scene, but had to follow the rules, so they made it sappy. And come on, TF and Graves had seen some shipping in the past before, we all know someone in the lore department is a crafty bastard.