[Y]ou imply that marriage is a surrender of sexual liberty. I don't think that's accurate. Marriage is Cary Grant and Rosalind Russell standing side by side in the closing scene of His Girl Friday, nattering on with the same jollity when handcuffed to each other as when not handcuffed. Marriage is indifference to handcuffs. There are always opportunities to escape. The strange discovery that makes marriage possible is that one has the liberty not tothe liberty to make the same choice, day after dayand that one happens to want to make a consistent choice. It is a paradox, at least.
Will one happen to want to make the same choice forever? Maybe not. Separation and divorce are always possible, in our world, and maybe they give marriage its poignancy. The possibility of separation proves that no two people stay chained to each other unless they want to. It even seems to be the case that people who want to stay chained to each other sometimes can't manage to. It is at any rate an error to think that marriage is a surrender of liberty. It is an exercise of it.