Myrtle Wilson and Daisy Buchanan have ? in common?

Myrtle and Daisy have Tom Buchanan in common..... Daisy is married to Tom, and Myrtle is having an affair with him.

Tom is literally all they have in common. For Tom, Daisy is the society-born "trophy wife" he needed that will provide him pure bloodlines for his children. Myrtle represents the passion that Daisy lacks (at least towards Tom).