...for a reason. Abusive behaviour is never acceptable and you have a responsibility to do something about it. Ignoring it is not an option. Whether emotional or physical, if the abuse is serious, please seek professional help.
People respond to life very differently according to their genetics, upbringing, experience and health, both of body and mind. Understanding this can help you see other people's behaviour more objectively. Sometimes the most outrageous behaviour can be a cry for help, although it's hard to see this when you're up close and it's personal. This is another reason for seeking professional advice.
People who treat others badly, nearly always suffer from low self-esteem. Bullies are usually themselves frightened.
Sometimes people lash out when they don't know what else to do. If you can sit down quietly with your partner, encourage them to tell you why they think they behave in this way. You may feel under attack, so bite your tongue and resist the temptation to get into a fight. Just treat this exercise as a fact-finding mission.
If they put the blame on you, once you've cooled down, ask yourself whether your approach might be contributing to their exasperation. Is there a better way of expressing yourself? Are you prepared to modify your behaviour?
If they take responsibility for their outbursts, this is a good time to explain how these make you feel and to suggest seeking help. No matter what issue you ever confront, by restricting your comments to describing the way it makes you feel, you'll avoid a fight.