i read about it and all what i understand is girls will cheat with a better man always if giving the chance ( and obviously there is always a better person )

i dont really have problems with girls but in the future i'd like to get married and find a girl who i will love etc but as far as i understand this isnt going to happen because girls will lose interest when they find a better person also i heard that women will cheat with more masculine looking men even if they are married and its making me depressed because i always thought that real live and these stuff exist

sorry if this is dumb i was never in a serious relationship , i am 18 and English isnt my first language