Is it okay? Of course.
I may not be a girl, but I could at least understand how one felt about it...
It can cause problems, however... the younger one would obviously feel intimidated by the age of the girl, as well as feel pride that someone older than them loves them.
The roles will constantly switch to who's in charge. The girl may also feel that they miss the childish attributes and turn to them as hope for a happy life. Or they find this person to be more mature than the older people (a common trait in today's love relationships) .
However, in a real relationship... one doesn't realize the age of the other...
Love goes through all bounds, and one doesn't see age in a relationship, rather, just the other person... who they are... what they are... everything they love about them... and love itself.
Heck, sometimes I forget how old Abu Dhabi is. ^_^;; She's younger than me, though....... at least, I think so... I hope my memory serves me well.
But Abu Dhabi will definitely add to this.