My wife has cheated on me twice

This week’s topic

My wife once cheated on me and l forgave her. Two years later she allegedly travelled to Tanzania to attend a seminar and when she returned, I got suspicions and started investigating her. I discovered that she was having an affair with an old man and we separated soon after. When I asked why she did this, she said the man had promised her greener pastures. I am sure I satisfy her sexually and these two guys are not as financially stable as I am. So what could have led her into those affairs? Why does a woman cheat on her man even after being given everything?  {Ephraim}