No, this can’t be a ground for divorce. You and your wife can mutually take divorce. But on the basis of not getting a promotion can’t be a reason to take a divorce. You need to talk this out with her. She knew your salary when she married you. Ensure her that you will get promoted soon. These matters need to be solved properly. Divorce is not the solution for any matter. You both can have a good talk and then think over this matter properly. You can involve her family too. Take opinions from your family and your in-laws. Then take action after getting a conclusion.