Here is what I would suggest :if age is the only negative, get all the positives listed as part of your genuine relationship:My file was rejected because my wife is 30 years older than me and now we are in the appeal . Is there any hope
Education
Upbringing /culture
Communication
Trips
Financial support
Any visa refusals etc - reason it out
Friends /family support letters
Why did you find that person as your significant despite age - traits that bond u together.
Be aware of all events - in terms why did it happen , when , where , how .both of you should be on same page. Be ready to answer questions that are shared only between couple.
In a genuine relationship one knows everything - emotions to express this things and to tell the story.
We all are living in 21st century when Silvio Berlusconi (83) can have a 30 yr old girlfriend - you know what I am saying .
Hope it helps .