The first time, both him and the girl were drugged so he couldn't do anything against it, so they had s*x. end.
The second time, he was supposed to marry a girl, but she didn't want to marry him, the MC would have agreed with her and wouldn't have married her if she didn't want too (since he didn't really wanted to marry her either)...
But that girl, instead of just talking with him, decided it was better to drug him and send her best friend to have s*x with him, to force him to marry her friend instead of her.
So he was drugged and needed to have s*x with a girl, but when he saw what was happening, he refused to have s*x with that girl friend and went after her instead. She totally deserve what happened to her.
She wanted her friend to rape him, well she got rapped instead, serve her well.
The Korean author says that the MC is a good for nothing and is just reading a script. Then there is a black person in the audience who come to criticize the MC, it's normal to counterattack. About the jokes about the Koreans (about kimchi for example) , a lot of people in every country do that about other countries (Americans who jokes about english people - english people about the french ones and their eating habits - french and the "belgians jokes" - the different countries who makes jokes about americans all being fat and in overweight because they eat burgers). You can see such jokes everywhere and it is not really a problem for anyone. So if the MC got critized by a korean, he took the occasion to make joke about them and take revenge at the same time
About the second times with Lee Anson, this singer deserve what happened to him, he goes in a country in their festival and take the places of 2 peoples which are from the country (That's OK) , He doesn't speak a word of their language and does "Lip sync" on the stage (let's say it's still OK) , after that when he leaves he doesn't show any respect to his fans, one of his bodyguards hurt one of his fans who has been waiting in the cold for hours and he doesn't even apologise to her (This is not OK, and even less if you count the previous things) . So the MC kicked him, he was right to do so