Kissing is believed to be what should be shared between married couples

There are cultures very strict about these romantic issues. But the best way to handle this is simply to adopt a relaxed attitude. I think 2 adults can do whatever they want as long as it is consensual and as along as they are responsible enough to accept the consequences of their actions. If an unmarried couple want to kiss, and even have sex, I think they should do it without any problem. Handling everything like the adults they are supposed to be.