Prince Henry of Wales dating a royal born Princess 10-8 years younger .Is it do able or not ?

As long as she's old enough to know what's she's doing, what's the problem? I think Diana was a little young at 18 to know what she was doing and what she was getting herself into. She should have waited until she was a little older and a little bit more "out there in the world." Other than that, the age difference doesn't matter. My husband is younger than I am. Not THAT much younger, 3 years, but the age difference is insignificant.

He is NOT dating anyone.
UK

No law against it. Prince Harry is 31 years of age, making a woman ten years younger 21 - well above the legal age of consent of 16.

Prince Albert of Monaco is almost twenty years older than his wife Charlene.

He can date who he wants it is no concern of anyone else. The age gap is irrelevant. Queen Adelaide was 27 years younger than William IV.

Whether or not a relationship is 'doable' surely doesn't depend just on an age difference? I'm not sure Harry has a steady date at the moment.

It's possible. Harry won't want to date some one too young, because of what happened with his mother and father.