How good goodbye is

There are different kinds of goodbyes. The easy one and the tough one. Goodbyes tend to be easy when you're saying it specifically, to someone you really don't give a damn, even if they care, when you don't, you'll just give them the impression of "I'll be back" even though you're not and it'll be fine, to you. Thinking "Oh, they'll just forget it, forget me". I know how easy goodbye works and what you will feel after, but I don't when it comes to the tough goodbye, generally, because I still don't have experience how tough one works. They say tough goodbyes are those you don't actually want to say it but you need to, just like a dying person, when they can't speak because of the tube connected to their lungs they'll go with the action by writing, touching, tapping, waving, or just giving you a look of 'love' or 'sorry'. That made me think, "Oh, even actions can express goodbye?" Really, how can a goodbye be so tough? How? Is it because they're loved... or.... they love? How does a tough goodbye really feel?