From personal expirence, you dont want to give too many chances to other people. I was in a relation ship for 5 years with some one who constantly put me down and called me names. My excuse to myself for his behaviour ( that he agreed with eventhough it wasnt right) was that he had a bad day at work, he didnt feel good, he was stressed, or he was just grumpy and didnt mean it. It took me a while to reach my limit and i regret allowing his behaviour to go on for so long. Another toxic relationship i have been in is with my own mom. This was brought to my attention by my wonderful therapist. She noticed that my mother and i have this re occouring pattern: my mom makes a bad choice , relasises she is in a situation she cant handle , then guilt trips me into helping her out. Its hard for me to admit this to myself, but i know its true. This has been going on since before i graduated high school. As much as it hurts to tell her no at the time, i feel a lot less drained and used in the long run. I love her dearly, but i have to cut her out of my life. I still see her on holidays and birthdays, but over all i feel better not having to solve her problems too.