Ever wonder why women cheat?
Here in Korea, some dude asked, "At what point does a Korean girl feel required to tell you that she has a boyfriend?" He went on to mention that he met a girl, she was giving him some clear IOIs like playing with her hair and touching his leg, he was clearly hitting on her, all while the girl never mentioning that she had a boyfriend.
Later, she tells him that she's off to travel somewhere on vacation. He tells her, "It'd be a shame if you were lonely. Who are you traveling with?"
She replies, "Boyfriend

"
And the dude's all like WTF
Well, first of all, this guy fails to understand that this sort of thing is not unique to Korean girls. Women all over the world are like this.
If a woman is attractive, she's always going to have guys hitting on her left and right. And, a lot of the time, she won't have a problem with cheating.
Think about it - if you had women hitting on you ALL the time, and if society pressured you in a way that made you feel like a "slut" if you had sex outside of a relationship, wouldn't you pretty much ALWAYS have a girlfriend, even if most of the girls you date really aren't that special?
What's that? You say you would, but you still would never cheat?
Well, have you ever experienced being tempted and seduced (many times very aggressively) by attractive people every single day?
It's so easy for a lot of men to pretend to have a higher moral ground because we simply have no idea what it's like to be a beautiful woman living in a patriarchal society.
Quit being so surprised when women who have "boyfriends" still flirt with you. A lot of the time it's not a lost cause. She doesn't love him.
What's that? You're bitterly thinking that you can never have a faithful relationship if attractive women are all like this? The good news for you is that the women who cheat on their boyfriends only cheat because it's a shitty relationship where she's not getting what she wants out of it, but she feels obligated to stay in the relationship for one or several reasons. The one's who actually love their boyfriends won't cheat, so if a girl loves you and you have a good relationship with open and honest communication, she won't cheat on you.
What's that? You say that the women who don't love their boyfriends and want to cheat should just break up with their boyfriends first? You aren't fucking listening. Most of the time it's just not that easy for women. Think about it.