Age difference in relationships

So my best friend has a thing for this older guy and she is really hesitant about it since the age difference is 12 years, I've been telling her that it's okay she's not a kid she's 27,and it's fine as long as he's a good guy and that she likes him.

What do you guys think? Please share the age difference between you and your spouse and maybe that would help her with the whole insecurity thing.