Well if you think about it "Eskimo kisses" (where you rub your noses together) became a thing because in colder regions your lips COULD in fact freeze together (much like sticking your tongue to a really cold telephone pole). So depending on where you live regular humans without horns face similar challenges with affection and mating. The only female that would have trouble doing any form of "kissing" would definitely be face 4 as of right now.
Maybe for them they kiss the tip of their index finger then touch the finger to their partner's lips? :) I've seen people do that to be cutesy, it could work here.
