Oh OP - in your dreams! He may be charming and a flatterer but is very unusual indeed to fancy a 65-year old woman in the way you seem to think he does.
You may think you pass for 40 but it is highly unlikely. My 41year old youngest D was recently refused a bottle of wine at an M&S because she didn’t carry ID. That doesn’t happen in your 60’s!
Perhaps he is gay and you are what is colloquially known as a “beard” -a slang term, American in origin, describing a person who is used, knowingly or unknowingly, as a date, romantic partner (boyfriend or girlfriend) often to deflect attention.
Perhaps he thinks you have money- there have been sad cases of gay older men befriended, fleeced of their savings and in one case I can think of, actually murdered by the lover.
Perhaps he is a natural flirt or charmer.
But don’t kid yourself, there is no fool like an old fool.