May husband and wife break bread together?

The Bible Monthly .

From "The Bible Monthly" 17 (1937), edited by W J Hocking

We see no scripture fobidding such an act, assuming the circumstances are exceptional and unavoidable. Where there is positive inability for a period to have fellowship with other saints, the presence of the Lord may be counte upon to be in the midst of "the two"according to Matt. 18:20.

They come together to "do this" not as husband and wife (see Gal 3:28), nor as "one flesh" (Eph. 5:31), but as joint-members of the body of Christ. They would in principle occupy the ground of the assembly of God in that place.

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Notes (biblecentre):

1. This answer from Bible Monthly is not to be taken as advocating ecclesiastical independency. However small an assembly may be, in order to "occupy the ground of the assembly of God in that place" it will (gladly) recognise that there are other like gathered companies and that the unity of the Spirit should be kept (Eph. 4:3). The article On Ecclesiastical Independency by John Nelson Darby is helpful in this respect. 

2. At the time of publishing this response on biblecentre.org (in 2020 - the year of Covid-19), the more burning question is whether you can respond to the Lord's request in small numbers (often not just husband and wife - in many parts of the world significantly larger numbers are allowed by the authorities* than the wo or three required (Mt. 18:20)). The response from Bible Monthly may be useful to some in their exercise in relation to this (or in developing such exercise). No individual believer is to be judged for being genuinely unable to attend. But the NT states that the supper is to be observed, as assembly, and that "till He come" (1. Cor. 11:26). Not even to the Corinthians was it suggested that there might be a case for discontinuing the breaking of bread for the sake of humiliation. Humiliation yes (both personal and collective), but nevertheless: "eat of that bread, and drink of that cup" (1. Cor. 11:28). 

*It goes without saying that all relevant hygiene measures should be observed so as to reduce risk to (near) zero.