The poem
Why should a foolish marriage vow, Which long ago was made, Oblige us to each other now, When passion is decayed? We loved, and we loved, as long as we could, Till our love was loved out in us both; But our marriage is dead when the pleasure is fled: 'Twas pleasure first made it an oath.
If I have pleasures for a friend, And farther love in store, What wrong has he whose joys did end, And who could give no more? 'Tis a madness that he should be jealous of me, Or that I should bar him of another; For all we can gain is to give ourselves pain, When neither can hinder the other.
marriage a la mode
Dryden ,in this poem, is trying to raise the issue of marriage built on shaky foundation and how such a marriage will not live long bofore the tow partners cheat one another.