Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
conjugal, connubial (adjs.)
Conjugal has two pronunciations, KAHN-juh-guhl and kuhn-JOO-guhl. Connubial’s primary stress is always on the second syllable. These synonyms mean “marital, of the married state, between husband and wife,” and although some commentators suggest that conjugal tends to stress the legal side of the relationship and connubial the emotional, it is difficult to prove that the distinction exists and therefore hard to be confident that your audience will always perceive it. Conjugal fidelity and connubial bliss are clichés that may help you with such distinction as there may be.
