Now I know why...
God one day decided to check in on Adam to see how things were going.
"Adam... How are things going?"
Adam replies that he considers himself quite fortunate to be living in such a beautiful place but he did have a couple of questions to ask if the lord didn't mind, of course. " No problem" said the lord, "ask away."
"Well Lord, I was wondering why you made Eve so beautiful? Not that I'm complaining, mind you."
"Adam I made Eve so beautiful so that you would like her." "Oh, well yes, I do like her very much. Thank you Lord, You made her so beautiful, but why is it then that you made her so stupid?" "Well Adam, I had to make sure that she liked you too!"