I think relationships fail because one or both people use anger to indicate an issue and also use anger to try solve it.

For me anger (in its various forms and levels) maybe is understandable, to some degree as we come to terms with new problems and issues in a relationship and fail in our dealing with them, but ultimately not an acceptable form of behaviour.

In others words, I cannot reward anger for anger but I cannot accept it also.
If two people in a relationship could agree on this complex idea then when we do slip into  our angry behaviour, we can be reminded of it by the other and simply put up our hand in acknowledgement and give an acceptable apology for our imperfect behaviour.

Being aware of the early signs of anger and agreeing to them is the next step.
Rhetorical questions, tone, volume, speaking over someone, for me, are signs of
anger in at its various levels. It is important that we monitor each other and also self monitor so as to remember to take a breath or break when we are heading towards a
heated exchange.

Using such traditional tools such as adjustable, accountable and acceptable language, and responding with appreciation, acknowledgement and apology, can go a long way to calming us both and playing by the rules.

Failing to get such agreements to these or any other rules of engagement, to me, is the beginning of the end, even before we have started, ha!