I know I will aggravate some people, but I strongly want to disagree with the "kindness is poison" argument. While I do agree, striving for strength should be done, when ever practicable, kindness has it's own merits. Kindness in fact keeps us from murdering each other. The police wouldn't have a chance to keep up with the murder cases and frankly, they wouldn't care much, would they? Social kindness e.g. inspires to people to investing their lives for a greater good, life developing medicine for example, instead of using their intelligence to become another wall-street broker. Or to formulate it as a stone-cold fact, society needs kindness or it will come to an end and nearly everyone will die (, except Kirby). Welcome back to the jungle. Also MC sounds like a fucking edge lord!
That "bitch" was quite ungrateful to her savior, true, but the point is, she herself wasn't very kind at all, was she? In the end she should have phrased that differently. But to be fair, "the weak should perish" is a argument aggressors usually use. Maybe something else happened to the girls loved ones and she simply snapped, when he used those words. In this case, it was his own stupid comment, that made her ungrateful. If he had seen it under the aspect of kindness, he might he understood that, they might have rekindled and made her his girlfriend. Who knows? He tried to give her a lesson in life and it didn't went well. Go figure.
The problem lies in not being kind enough! (And those bastards'n'bitches abusing kindness.)
And also, he bought that elf girl. Following his own advice -> RAPE TIME! See where not being kind would lead him? Back to his empty castle. (If he survives, that is.)
Judging from his behavior the MC himself is kindness in denial incarnated. He really isn't the best representative for the things he preaches. I rest my case (for now).