Some relationships truly do need to end. If your partner is abusing you, you need to get out of the relationship as soon as possible. If you're on other side, and you're having trouble controlling your temper, then you're obligated to break up with the other person for both of your sakes.
Aside from the obvious, when should you consider ending a relationship? When it's clear to you that the two of you no longer want the same things in a relationship. If the other person wants to get married and you don't, that's a sign. When you find yourself moved to cheat on them with someone else, that's a sign.
Ending a relationship shouldn't follow a big fight. This is how good relationships end up being broken apart when there's no reason they had to. When considering breaking it off with the other person, you need to have a clear head about the entire relationship.
Once you decided to break it off, you need to do it the right way so that you can both move on. There are three basic guidelines you need to follow:
Don't Play Games - Nobody likes to break up with someone. That's normal, but there's a temptation to try and make the other person do the dirty work in ending a relationship. Mostly subconsciously, we pick fights and play games to try and antagonize the other person into breaking up with us.
This is a trap you need to avoid. Be direct, be honest and be proactive; make sure you treat the other person with respect. Trying to goad them into breaking up with you will simply make you both miserable.
Do it in Person - Breaking up is a very painful experience for both parties. It is very tempting to bring the relationship to the end by email or phone or, these days, text message. That way, you don't have to see the look on their face or if you leave a message, without even talking to him.
But obviously, this is no way to end a relationship. If you do not interact with the other person will breaking up, you won't have any kind of closure. This defeats the entire point of making a clean break. Do both of you a favor and break up in person in a relatively private place.
Be Honest - You need to tell the other person exactly why you are ending the relationship. This isn't easy, because they will have tendency to try and talk you out of it, but the truth is that lying to them about the reasons doesn't help either of you. Be honest, even if they don't want to hear it.
If you follow these three tips, you will find ending a relationship to be a much smoother, much more effective process. Be aware, though, that along the way, you might find that the problems you have are fixable. If this is the case, you need to find some resources to help you mend and repair the relationship.