I Need Feedback!

So, I'm facing a little dilemma with Book 2: one of my main characters (a girl--not Norah) is 16 years old when the guy she ends up falling in love with is born. 

Now, she's Cobbogothian, and Cobbogothians live for 1,000 years on average. They mature to adulthood the way we do, but once they hit adulthood--18 yrs old--their maturing slows way down and they age much, much, much slower than us.

So technically, a 16 year age difference to them is like a 3 month age difference to us. It's a little Edward and Bella-ish, I know, but when the tables are turned and the girl is the older one, I wonder if it's less okay.

Does anyone have a problem with this? Feel like any major taboos are being broken?

Thanks!