think you meant ahegao. There a lot kind of -gao, ahegao is just one of the most popular. It supposed to mean the girls feeling pleasure so much it fucked their brain out (also used just to say they cummed). So people just like to see the girls feeling good.
Nothing wrong with you because everyone have their own preferences. If dev want to add setting to disable the ahegao, they might do it only after the game is finished.