This is a cultural issue really. You can't say one country's attitude is right and anothers is wrong. You just have to respect the feelings and social 'rules' of where you are.
You say you find all displays of affection unpleasant, but do you really? The other day I saw an elderly couple, they must have both been in their 80s, holding hands as they walked along the street. I find that very sweet to see, not unpleasant at all. Would you have found that offensive? I guess that perhaps you would, as some cultures find any physical contact like that offensive, but to me it is a nice thing to see. I'm happy that they are happy and in love after a lifetime together.
I do agree that it can go too far though and sometimes it IS done just to create an impression or gain attention. Anyone who sees a couple of teenagers all over each other in public is thinking 'yuk', no matter where in the world they are! But there is a big difference between small genuine signs of affection and this sort of 'display'.