Is love really a moment that last forever??

Recently I heard of another failed marriage from a friend. I known him for over 10 years, we go through BMT & Air Engineer Training Insitiute together and post to the same air base. To me, he is a nice guy. He doesn't smoke, doesn't drink, doesn't club and very serious at work. When I received news of him getting married, I was very happy for him and was almost sure that it would last. Then he went to US for a couple of years with his wife and had a baby there. After that I lost contact with him... A few weeks ago, when I was out with Ken drinking, he came along. I didn't think much about it at first as I thought maybe he just wanna meet up since we hadn't been in contact for years. While chatting over some drinks, I came to know that he is current in the process of divorce. His wife fell for another man and now they are fighting for the kid.

Nowadays, I heard a lot of failed marriage all about wife falling for another man.... Why is this so?? Even when I was out drinking last Saturday, a gal friend of Ken who was married came along with another man. I really don't understand...... What exactly is love? A moment of lust or a moment that last...