Being polite is being courteous, being avoidant of the boundaries of other people, it's not causing a scene. Being polite is asking before coming over. It's "nice." It gives forewarning and assumes that the other person may not always be ready. It precludes all opportunity of understanding, of friction in the relationship. It's the "sure, if you want to" that hides every desire you have until it disappears.
Being kind is being vulnerable, taking down those boundaries that separate you from other people, and doing what you can to make them happy. Politeness is the surface illusion of kindness; it is admitting that you have become a coward in your heart and are unable to give someone something they want, something you want to give, unprompted. It is constantly asking "is it okay for me to be here?" "is it okay for me to do this to you?" It is saying that the quills of the hedgehog are hurting you, so you stand back and never touch their skin.
You can feel her hot breath on your face, you're dizzy, it's too warm and you're sweating on the couch. Everything in your body, every muscle ready to move, every neuron filled with a single repetitive thought, screams you want to taste the inside of her mouth again. It feels polite to not smash your face into hers you think. Unconsciously, you, maybe even accidentally, put your hand on her inner thigh just because that's where your arms fell as you lay. She rubs the back of your hand to tell you not to move it. Coward that you are you think, what if she doesn't want it? Maybe it was a mistake that she gave me a taste before, maybe it was all a big misunderstanding, it was late and it meant nothing. You betray her memory. All the while, you stare, eyes darting between her eyes and her lips, softly spread apart. Your tense, ragged breathing continues, mentally searching for a foothold, the polite way to ask for permission again. "Erm miss, can you stick your tongue in my mouth again? Pretty please?" You'd probably have backed off, scooted away to a safe distance if you could, but there's no escape, she's on top of you, pinning you against the back of the couch like you wanted her to. After 4 whole seconds, the trial ends, and she breaks the silence: "Why don't you kiss me already?" It was probably off putting, your "politeness." Her tone is semi-accusatory, impolite even, she's feeling disrespected. You give her what you both wanted, intimate nonverbal communciation.
You communicate this deep emotional appreciation for her very being, her soul. Your motions, the way you touch elevate her above the material. It is sensual, rubbing, massaging. She communicates that she desires your body, all of it. It's grippy and consumptive with the hands. It's the pain that precedes waves of pleasure. It's a mismatch, but you hope that she means that she really wants to fuck you because she's attracted your mind. The kissing and groping progresses and true kindness, not politeness, appears once again as she gives you, unnannounced, sudden clarity, the clarity you craved and the clarity she needeed to deliver. You weren't imaginging it, she doesn't want a relationship, she wants to be friends with benefits, and she tells you this before you delude yourself into anything else. The agony of months of deliberation punctured and deflated with a single sharp comment, one born out of the way you touch each other. This whole arc could have lasted so much longer, and you are thankful that it didn't.