It's hard for me to be objective on this one, because i've always been the lonely guy, looking at the amorous antics of couples & envied them, but I'll try to be fair.
I guess if it's something like hand holding and-or a quick peck on the cheek, it's ok. But if it's a grope-fest, love-wrestling match, where both are trying to be the next XXX Movie Stars, then No. To me, that's just obscene & serves no purpose than to rub it in people's faces. & make those around them uncomfortable.