Of course every relationship is different, and it's impossible to tell another person when it's time to call the match finished. There are a few major signs to watch for that generally point to a relationship being a lost cause. Some of these are:
1. It's new. If your relationship is brand new and already bloodied and overbalanced, it's probably time to call it quits. Both in life and in Internet dating, if your relationship has problems only a few weeks or a few months in, the chances of it working out in the long run are slim.
2. You're not really happy. Having one large problem with the relationship can help bring a whole host of other problems into focus. If, when you look at your relationship, you realize that (in addition to the larger issues) you don't really feel happy together, there's nothing to be saved.
3. The relationship is unhealthy. Just like the above, having other problems in a relationship can bring a bigger, and more important problem into focus. If your partner is abusive, or you're in a roller coaster relationship, the problem that comes along to end the relationship can be a blessing in disguise.
Think its worth staying in the ring to duke it out a few more rounds? Then there are a few things you need to do to help heal your injured relationship and live on to fight another day.
1. Acknowledge Hurts. In order to keep this relationship from collapsing as soon as you get back in the ring, you need to look at it clearly and acknowledge what has hurt you. This means telling your partner honestly how you feel, and why. If something happened that you need to heal from, you'll never heal if you don't make discussing it a part of moving forward.
2. Discuss What Isn't Working. There's is a reason or reasons why this relationship isn't working well. Instead of kissing, making up, and pretending these reasons don't exist, you need to discuss them face on.
3. Decide How to Avoid those Mistakes. Once you've figured out what is going wrong in your relationship, talk to your partner about ways to prevent these same issues from cropping up again and again.
In short, relationship problems don't go away on their own-- not in the real world, and not in Internet dating. You and your partner have to work through your problems and find solutions for them together. Only then can you move forward, ready to fight (and maybe even win) together.