If it’s a committed relationship, it takes a lot. The other person has to be unresponsive to your attempts to arrive at an agreement of how the relationship will continue.

So, if it is abusive and you try to have it end being abusive, and it continues, break it off. If you are sexually exclusive bu the other continues to sleep around, break it off. If the other person wants you to be exclusive, but you can’t honor that and agree to it because you want a sexually permissive relationship, break it off.

If it’s a new relationship, then break it of cleanly once the other person becomes unresponsive.

When she stops putting up with my bullshit.

When you feel unhappy in your relationship more often of than you feel happy, and you or the other person is unable or unwilling to make any useful changes to repair the situation.

If there is abuse (could be physical, could be verbal or psychological).

If you or the other person is no long in love and one or both of you is not willing to continue on in a relationship that is simply platonic (for some couples this is perfectly comfortable for them).

If the other person treats you as a second class citizen, or treats you as if you are not very important. If one or both people treats the other in a careless or reckless manner.

If the other person has unrealistic expectations about you. I’m thinking more in terms of what he/she might expect from your behavior (what you wear, who you associate with, how much of the housework falls on your shoulders, harsh or old fashioned gender expectations on how one should act). I guess you could say a person like that is controlling.

If either of you has unresolved issues that can’t be fixed/changed, such as one person wanting children and the other person not wanting children.

When she married another guy.
Broke my heart.

I got better

When, after six months together, he obviously was not interested in marriage, I wasn’t going to wait around any longer, so I stopped it. I told him that was enough. We stayed friendly, but only friends. When I saw him on the street months later walking with another girl, he was so obviously in love, it made me smile. I was really happy for him.

When you start thinking that it may be time to call it quits is usually the time when it’s time to call it quits.

For me, that moment was when I felt that I had done everything in my power to make it work, and it still was not a happy relationship.

@Kardamom Ya, or the girl expecting the guy to be rich.

@mrentropy Not necessarily.