That is definitely a tough one! Nineteen is still that age of "I know what's best for me and don't try telling me I don't. I'm old enough to make my own decisions." So keep in mind that if you push the issue to much, you run the risk of pushing her away.

I would recommend that you first take a good look at the reasons you do not like this young man. From here you have a working list to discuss with your daughter when the time is right. Perhaps even more important in your role as her father, you can role model the correct way to treat a woman for example (or whatever personality flaw you see in this boy).

When it comes to the bottom line, I would recommend that you talk openly with your daughter and express your concern in a non-threatening way. Let her know that you don't hate her boyfriend, you just really love her and want what's best for her. Above all, let her know that no matter what choice she makes in her love life, you'll always be her Dad and you'll always love her.