Someone did or said something that pissed you off. You don't want to say something you can't take back so you stop talking to them. They keep talking to you but you refuse to acknowledge them. Some time later you bring up why you're still mad and they look at you like you're speaking Swahili. Now you're angrier and ignore them even harder. Sound familiar?
Ignoring people is a passive aggressive way to manipulate a person. You want someone to start or stop doing something but they deny your request. Ignoring the person is supposed to use their desire to interact with you as a bargaining chip to get what you want. But it doesn't work. Here's why.
They never really liked you
You can't use someone's desire to interact with you as a bargaining chip when they already don't give two shits about you. In fact, whatever they're doing or not doing to piss you off might have been intentional to begin with. Which means they have successfully manipulated you, but you're mad by yourself.
They have no idea that you're mad
Most people get mad then immediately ignore. This means the person you're mad at has no idea. If they don't know you're mad, they don't know what they did wrong and therefore won't care. This leaves you bitter, ignoring someone who hasn't figured that out yet.
They don't care that you're mad
Don't be so quick to assume they are the problem rather than you. You might be a very petty person who simply cannot handle the truth. Why would they care that you're mad?
You're preventing progress
How can a person right a wrong if you're not allowing them the opportunity to correct their mistake? If you don't want them to make it right, then why play this game?
If someone makes you mad, tell them. Ignoring them is okay if you need time to pull yourself together. But don't let more than a week pass before you communicate your feelings. Too much time breeds indifference.
Give that person a chance to make things right. Allow them to apologize. Allow them access to you to speak with you and work it out.
Don't play games. If you don't want to let them correct their mistake, tell them. The dumbest pettiest thing you can do is stay friends with someone on Facebook with whom you no longer wish to speak. You'll make yourself look ridiculous to the person you're ignoring, as well as your other friends and family. Being unreasonable and illogical makes you look unstable.
Get over it and let it go, work it out if you can, or end the relationship and move on.