We have all heard about our "right to remain silent" or "Miranda" warnings if we get arrested, yet individuals seem to rarely exercise this right in real life situations. The problem is that people want to explain the situation, or are uncomfortable with silence, or don't like confrontation. Regardless the reason, it always hurts your case. Furthermore, police officers know this and are trained specifically in how to get people to talk when they shouldn't.
Police officers use numerous psychological tactics to pressure people into waiving their constitutional rights. They play good cop / bad cop. They tell you they won't arrest you today, get you to talk, then arrest you tomorrow (I've seen that happen). They tell you that only guilty people need attorneys, and that they just want to get your side of the story. Bottom line, don't be fooled. They are building a case against you.
Domestic violence cases are complex in that the cases involve people who care about each other and don't really want their loved one going to jail. Many times there are no witnesses. It is a he said she said situation that ultimately got heated, out of hand, and sometimes involves both parties behaving badly. Therefore, it is imperative to remain silent. When the police arrive on the scene, they have no idea what happened so they try to figure it out by taking statements that get forwarded to the District Attorney. The problem is that when an "authority" figure asks a questions, many people feel compelled to answer. Many times officers ask specific questions to elicit a reaction out of individuals. Don't get caught up in their tactics!
The only time a person should say anything, is if they were defending themselves. Even in this situation, it is imperative to say as little as possible and let an experienced attorney handle the details. If a person is defending themselves, and the cops show up, tell the police officer that they were attacked, and they defended themselves, and (if appropriate) they want the aggressor arrested. The reason for this is (if the cop is diligent) the officer will put your statements in a report, which if you had to go to trial, would be brought out before a jury.
However, even providing a statement to the police that is beneficial to your case becomes complicated because it may implicate your loved one and end up getting them arrested. Another reality is that if the police are called out on a domestic violence call, usually one person up getting arrested. If they can't determine who the aggressor was, then sometimes they arrest both individuals. However, if this happens they have just provided a defense for both parties as they couldn't even tell who was the aggressor was.
All this being said, the best thing you can do is be kind to one another and hopefully avoid such a situation. If a situation between you and your loved one begins to get out of hand, take a time out, get some fresh air and cool off. If you notice you or your partner stress manifesting into verbal or physical abuse, contact a counselor and seek and get the professional help you need - before a court orders it for one or both of you.