Nothing. Your daughter is 30. Your approval or disapproval is irrelevant. People have to make their own mistakes. At 30 years old she is too old for you to try and control. I realize you made sacrifices for you grandchild and daughter, however those sacrifices do not give you power over her. You want find out about this boyfriend, have them over for a family dinner. Get to know him. Be kind. If it doesn't work out she will have to kick him out. Just know that the more you protest the more she will cling to the idea of this man.