The gemara teaches ish v’isha zachu Shechina beineihem, if a husband and wife merit, then the Shechina dwells amongst them. If they do not merit, then fire consumes them. The name of Hashem, י-ה, is found in the words איש and אשה, representing Hashem’s presence. If they do not merit, then Hashem withdraws His name from among them, leaving אש and אש, where the marriage is consumed by the fires of domestic discord.
A deeper way of understanding this is that many people think that to have complete shalom bayis, you need a complete identity in both spouses where the spouses are identical to each other. But the truth is the opposite. If it is identical, then you have א,ש, which spells אש. It is only when you have the other letters, the י of איש and the ה of אשה, that Hashem can dwell amongst them. When spouses get along despite their differences, that is when Hashem dwells there.
