Try again

[sandmaster]

I have asked this before without success but I suppose it is like searching for a needle in a haystack:
About 45 years ago, when I was 16, I borrowed at random a book from the local library. It opened with the hero sharing a bed with his wife the night before he goes to prison. She is cold towards him. When she is asleep he tries to get her into a position for sex. She wakes and tells him not to be stupid. Sounds naff but it was one of the funniest books I've ever read. Does anyone know the title or author?