Guys will be happy to commit to her when shes young and pretty but once she gets older there no stopping them from being unhappy and wanting divorce. Since guys will always be most attracted to women I'm there youth theres a high chance theyd cheat on there older wife if they got the chance. Also theres the fact that guys arent made for monogamy and that the Coolidge effect exists therefire why would a women want to dedicate her youth to someone who wont even be attracted to her when shes older.