Talulah Riley
After they tied the knot in 2010, SpaceX employees said they were able to determine Elon's mood based on Talulah's hair color. He was "happiest when her hair color approached platinum." In January 2012, he announced their separation by tweeting (at her), "It was an amazing four years. I will love you forever. You will make someone very happy one day." They got a divorce, remarried a year later, and then divorced again in 2016. Can't say they didn't try!