For me Im with someone who is 9 years younger.
We meet approx 10 years ago and now Im 42.
It really depends on the person, even though we
have an age difference and have absolutely nothing
in common my partner seems to think on the same level
as my age so does not seem to be an issue.
I do not believe I have held her back as she has
always wanted to be around me more than her friends,
I actually force her to go out with her old school and uni friends.
There are just some people attracted to older people and you will never change that.
Play the loving boyfriend but also let her lead her own life which is what anyone in a relationship should do.