You are definitely freaking out: I have always preferred dark haired women, but I'm happily married with a blond girl, simply because there are many other aspects in which she provides me with ample satisfaction. It's just one aspect, not the sum of things.
He seems to have had an interest in you for more than a year (he's patient...), and is inviting you for your birthday. What else do you need to accept he's interested in you?
One thing is certain: you will never be able to satisfy 100% of the expectations of any man living on Earth today. So quit fretting about it, it's distracting from what's really important: he's interested in you, accept those feelings and cultivate them.