If you are in a position where you are seriously thinking about whether you should end a relationship there are questions you can ask yourself to see whether you should continue trying to stick it out.
If you don't have children and you're not married, if you have one of these two serious issues, your relationship may not be worth saving. The two issues I think are critical are trust and respect. If your partner has cheated or you are disrespected or verbally/ physically bullied it may be better to walk away before you get in deeper. Disrespect or anger issues are very difficult to change. For that change to even have a chance of taking place the person must recognize and take full responsibility for their actions. If they blame you or minimize what they are doing they are basically telling you this behavior will continue. And disrespect or aggression in any form is poison to a relationship. Now matter how much love you start out with it will change over time and you will no longer be in love with the person. There is only so many times someone can treat you badly before you call it quits. If you put that together with making a change as big as what you do when you're angry and you have a very tenuous situation. Making any kind of change involves making progress and then slipping up. In this situation slip ups mean further damage to a relationship. Making this kind of change usually means the person with anger problem needs to do this on his or her own.
If there has been infidelity and the person cheating has not taken full responsibility and been completely honest about what has happened then you will not be able to rebuild that trust. If you don't trust your partner you will begin to withdraw. I have had many people come in years after an affair saying they are no longer in love with the spouse who cheated. Over the years they became numb and were unable to fully give themselves to the other person. On the other hand if the person is willing to do everything in their power to make things right there are things you never thought you could get over that you do get past. But when it comes to cheating even if you realize the person wants to change it may still mean you don't end up trusting them. This is especially true if you are in the first few years of a relationship. If you don't have a history to draw from it is hard to honestly see the person as someone who is basically good but made a mistake. And some version of that is where you need to end up if you are truly going to move forward.