I normally will give a person 3 chances if they continue to make the same mistake and continue to hurt me or my family. After this it is very hard for me to forgive them again. Because a strain has been put on our friendship and it seems the more you forgive them, the more they take advantage of you.
Now, on the other hand, a relationship between husband and wife, it is necessary to forgive and move forward. This can build the relationship and help each other. If you truly love your husband or wife it shouldn't be an issue to forgive the small things in life that happen. But if either one of the partners cheats on the other, then this is not forgivable. In this case, it really hurt and the trust is broken. This can be one of the hardest acts to forgive for anyone.
I normally don't forgive a person who screams at me and embarrasses me in public or in front of their other friends to show off. However, I had a really good friend that I really liked to be with and do things with. She had a bad habit of yelling at me or acting like I was her servant in front of her friends. Finally, it was too much and I could no longer overlook this act. I finally just quit calling or accepting her invitation to do things with her. I have never treated a person with disrespect and it is hard to accept a person disrespecting me all the time. I can forgive more now than I could when I was younger. However, there comes a time when you run out of forgiveness and just have to say good-bye.