This was a question that came into my mind after finding out about an old acquaintance’s break up with his long-time girlfriend.
When is it too much? I have a simple belief for this, actually.
Say, when you’re with someone and he (I’m using the general pronoun here) inadvertently hurts you, that can be forgiven. You talk it over between the two of you and end up with a better understanding on what happened and what to do to avoid it. But for that person to hurt you again for the same reason, then that means something is wrong. Being hurt for the same reason is not just too much but I also see that as stupidity.
For me, if someone truly loves you, he will make sure that he does not hurt you for things that he could have already avoided. If it does happen again, it must be due to outside interference, unavoidable circumstances or any other factors that are outside of your control.
That’s my simple take on it.