Why does abuse in marriage escalate?

Because the anger in the abuser keeps getting worse & worse as time goes by. You are dealing with a mentally sick person filled with hate for themselves who put it on others. I've been involved in EVERY kind of abuse including Domestic Violence having to get restraining orders. Only a professional could ever hope to get to the bottom of the anger, then work on getting rid of it. It WILL keep getting worse as time goes by, that I CAN promise you. Remove yourself from them before it turns to Domestic Violence as it WILL...the best to you...:)