Whether or not you tell your parents about him or not, it's a lose-lose.
This could cause her to withdraw from the family in many ways and cause even bigger issues.
Every situation is going to be different and how parents handle their daughter's dating relationships is going to be up to them.
The mom could try and forbid it, but has no way of doing what she would need to do to enforce it. Keep lines of communication open with your daughter, talking to her often about sex, love, family values and teen pregnancy.
This mother is seeking advice about her soon to be 17-year-old daughter's relationship with a 21-year-old man.
And if you tell them, you'll deal with all-out fights.9. No matter how special he insists you are, the chances are that he's been dating younger girls for years.10. I know hearing that is like sticking a fork in your chest and ripping your heart out. Maybe you're sure that you won't be dramatic about it, like "other girls." But that shit tends to sneak up on you. And maybe somewhere down the road, things will be different for both of you.