you said he is 51. I think maybe he is feeling he is losing his youth and maybe going thru midlife crisis. alot of men go thru this at this age. as the old saying goes...this too shall pass. my dh is not like that anymore. he is 55 and since about 47 says he is old. we are rarely intimate anymore. but I was married before to an older man and he was very much like you are describing your husband without the drinking.