Does Monogamy exists?

My dad just came back from his Vietnam trip and we were chatting over dinner on how hospitable the Vietnamese are. My dad was saying that his friend's wife treated him a very good dinner and I went: "Oh, his wife went over too?", and my dad replied: "No, he got another wife there."

Well, I was not taken aback since I know that my dad's friend is not anything of the "Mr Nice Guy" type but I was, however, surprised at how my dad said it in such an easy and guilt-free manner.

I asked my dad what will he do if my future husband has a another wife in another country and my dear daddy gave me the oh-so-logical answer: "What to do? He needs to depend on this relationship to run his business in Vietnam, they are not registered anyway."

Registered or not registered is none of my concern. My concern is the value of marriage in a man's point of view. Is earning money the monogamy practice-free card? Do men really think that they can make use of this excuse to breach their marriage vow rightfully? Aren't they guilty conscious?

If the importance of monogamy is poles apart between women and men, what is the value that holds a marriage, or rather, relationship together? In the history of human existence, have we, the mankind, ever practice monogamy?