Some do and some don't. Those that do, (like my husband and I) are not putting on a show, but don't care what others think. Those that don't may be prudes or don't want to "stumble" anyone - you know how that one goes. Or else they may not have that in their relationship.
I don't think in most cases it's a question of loving the other person. It's just about feeling comfortable showing affection in public.
Juni