A dictionary of Proverbs (Oxford Paperback Reference)

couple see a DEAF husband and a blind wife are always a happy couple.
The COURSE of true love never did run smooth

• 
  1595 SHAKESPEARE Midsummer Night’s Dream I. i. 134 For aught that I could ever read.. The course of true love never did run smooth. 1836 M. SCOTT Cruise of Midge I. xi. ‘The course of true love never did run smooth.’ And the loves of Saunders Skelp and Jessy Miller were no exception to the rule. 1980 Tablet 26 Jan. 89 The course of true love could never run smooth with Sybylla’s temperament. "love, blighted
  

course see also HORSES for courses.
court see HOME is home, as the Devil said when he found himself in the Court of Session.
cover see (noun) you can’t tell a BOOK by its cover; (verb) CHARITY covers a multitude of sins.
coverlet see everyone STRETCHES his legs according to the length of his coverlet.
Why buy a COW when milk is so cheap?
An argument for choosing the least troublesome alternative; frequently used as an argument against marriage. One of the few proverbs in the form of a rhetorical question; cf. why KEEP a dog, and bark yourself?

• 
  1659 J. HOWELL Proverbs p. ii. It is better to buy a quart of Milk by the penny then keep a Cow. 1680 BUNYAN Mr. Badman 293 Who would keep a Cow of their own, that can have a quart of milk for a penny? Meaning, Who would be at the charge to have a Wife, that can have a Whore when he listeth (wishes)? 1895 S. BUTLER Note-Books (1926) xvii. It was cheaper to buy the milk than to keep a cow. 1942 S. ACRE Yellow Overcoat v. ‘He ain’t marryin’.. any more!.. ‘Why buy a cow when milk is so cheap, eh?’ 1984 W. TEVIS Color of Money vi. ‘I don’t have a wife.’ ‘That’s the best way. Why buy a cow when you can get milk free?’ 2000 E. GUNN Five Card Stud iii. 36 She said she thought people who wanted to live together ‘ought to get married and be done with it.’ ‘I
  

don’t want to be done with it,’ Trudy said. ‘I want it to go on and on.’ ‘Fat chance of that.
Men don’t buy the cow if they can get the milk for—’ ■ marriage
cow see also a BELLOWING cow soon forgets her calf; BETTER a good cow than a cow of a good kind; it is idle to SWALLOW the cow and choke on the tail; THREE things are not to be trusted.