I think in general, though, it depends on what your boundaries are as a couple. As a couple, you should have set boundaries(some are more open than others, of course), and if those boundaries are crossed, there should be consequences. If there aren't consequences, people's self-respect and self-esteem get damaged, and that's not good.
Yeah, if there's any doubt about the extent of your liking or loving, unfortunately there's no such dichotomy in real life, how much you're willing to hurt them should be a pretty good test. The Japanese way of trying to keep things under wraps while letting your feelings dictate the proper course rather than talking it out and setting explicit boundaries ahead of time is a good approach, though, in my opinion.