Sex takes hours?? Unusual problem!!

I am 52 years old. The man I am dating is 45. I love so many things about him, he’s funny, witty, slow to anger and the list could go on and on. He is a good kisser and I haven’t been this turned on in years, BUT he takes FOREVER (2 to 3 hours) to reach orgasm and what started out as great for the first half hour has now turned into exhausting ordeal. Sex takes hours. I’ve never heard of this before. He says it’s not me, that I turn him on wonderfully. He just says he’s always had a long “hang time”. But, I don’t know if I can stay in this relationship because of it. I don’t want to break up with him, but I just don’t have the energy to keep up with him and I don’t want to dread having sex. Is there anything I can do or a doctor could do??? He does have back trouble and frequent kidney stones, but like I said, he has been like this all his life. He says his ex-wife kicked him to the curb because of it. I don’t want to reject him, but I’m at my wits end. Help me if you can. Thanks so much! MJW