I am a 29 year old male, and early in my relationship the sex was defintely a big part. I would hope after 6 months of being with this partner you could bring it to his attention once more in person and let him know how much its affecting you. Of course, in a loving and serious tone. I’m sure if he cares about you he will be honest and open with you about what it is.
I would venture to guess even at 39 a male would still have a high sex drive. I know it surely goes doewn some but I would hope at the beginning of a relationship its still present. I think since its bothering you this much just bring it up again with him in person. The beginning stages of a relationship are some of the best times to be honest with your partner because they get to know who you truly are and you want them to know. And with seeing him face to face and bringing it up you could see how he reacts to the question. 6 months is a good amount of time to have your ‘needs’ met.
Everything always works out in the end, if it is meant to be it will find its way. I wish you nothing but the best, Carol. <3