I saw an article a month back about a father-of-three who set his wife on fire, killing her. It was, obviously, horrible. He did it right in front of their kids, too.
You look through the article and there are a bunch of pictures of the husband and wife, looking like two totally normal people, perfectly happy together. The husband looks like a bit of a nice guy, and the wife is always doing this weird shrug with her shoulders and kind of leaning away from the guy, but she's smiling, and it's a genuine smile. They look like a very typical, average, regular couple.
Then you read about the chain of events that led up to this guy going psycho on the wife.
His Australian wife kicked him out, presumably after they'd had a ton of fights. She then filed a restraining order against him, and started the divorce process. He, as an American citizen, believed he'd get deported from Australia, and presumably be cut out of his children's lives. His business was in Australia too (I don't know why he couldn't just get a business visa, but maybe he couldn't, or he was too upset to think of that).
The neighbors said they never heard the couple fighting, and the guy was always friendly, loved to talk, but was also "obviously distressed" when he was in the process of being kicked out.
If you read the article about this, it's clear the guy just went deeper and deeper into a depression spiral after his wife kicked him out. She began making accusations against him, too. Finally he snapped and went back and set her alight.
This article will be about a very important topic: that when people take unilateral action against you, as the wife was against the husband here, you also must respond in turn with unilateral action of your own.
However, you need to understand this, and approach it strategically, with appropriate moves and strategic timing -- well in advance of the point where you snap, and resort to desperate, destructive/self-destructive unilateral action, of the sort people turn to when they feel they have no way out.