I'm about to continue my education at the same place for grad school and my new girlfriend is a sophmore about to be a junior. She is young for her grade but is a junior while Ill be in grad school. My parents like her and also believe she is more mature than most 19 year olds but her parents are not as happy. Especially her dad is concerned that she she's too young to be dating a guy who is graduated undergrad and ready to settle down while she still just a junior. I admit I wasn't mature enough for a relationship at that stage and see his point but she is more responsible at 19 then i was and she said she doesn't care what he says but we have to deal with it a lot considering it her family and have been tigether for 6 months.
A 3 year age difference isn't that significant. The fact that you're in grad school, and she is an undergrad means nothing. What if it were the case that you two started dating when you were both undergrads? Her father probably wouldn't have cared.
Your girlfriend is not too young for you. That's a great age difference even in high school guys who are 16 with date 13 year old's because it's the same as 19 dating 16 year old's because if you round that down your ages over lap and it's not that big of a difference. Plus your can't be ready to settle down yet. Don't settle down until you've reassured you both have good carreer jobs and experience a little fun more. I man she's not even legal to drink yet. so I say wait till she can legally drink to even think about settling down. After that Do what you will okay. Maybe see how you do in a few years together.