Well, the thing is Kissing is public is frowned-upon in Sri Lanka. Sometimes going out as couples and gentle holding of hands may bring unwanted attention to a couple. This is more prominent in public transport systems. Since Sri Lankan culture regards mingling of sexes outside marriage and dating unacceptable and as a social taboo, that sort of "Public Display of Affection" is not tolerated.
In capital Colombo, it is a common scene that couples holding hands and going to public places but no kissing occurs as far as I know ( I've never even gone out with a girl BTW ) but the general notion is "YOU CAN'T KISS" in public places.
There are cases when police intervening couples, taking them to police stations and even pressing charges against them of public indecency. I don't recommend doing kissing or any sort of Public display of affection. We should respect the culture.