Spouses feel threatened when their mates are angry. Some feel threatened for their safety. 

Most of us have felt that anger is a threat to our marriage, and it is. 
Anger verifies a that a line has been crossed. Sometimes that line is legitimate, sometimes it is not. 

Also, anger kills marriages because it kills spouses. One 1985 study said that 9% of murders were by spouses. (1985 was the year my wife and I married). 

For some, anger is a management tool. When a person is married to a timid mate, anger is an ideal way to control the spouse. 

Consider this from the Old Testament: Psalm 86:15: “But You, O Lord, are a God merciful and gracious, slow to anger and abundant in lovingkindness and truth.” This says God is slow to anger. 

Why is God slow to anger? Because He is not scared of anyone. 
God is not scared for His own future. 
What can anyone do to God? Nothing. 
So then, He has no reason to fear anyone. Quick anger serves Him no purpose. 

The next time there is quick anger in your marriage, ask the question, “Who is afraid of what?” 
Is anger ever justified? 
Of course it is, but do a reality check before jumping off the deep end. 

Here is one quote from the New Testament, and one from the Old Testament: 
James 1:19-20: Know this, my beloved brothers: let every person be quick to hear, slow to speak, slow to anger; for the anger of man does not produce the righteousness of God. 

Proverbs 16:32: Whoever is slow to anger is better than the mighty, and he who rules his spirit (is better) than he who takes a city.