The reality of being the friend who is so close to you and tries to make you not make such mistakes, watching you go and make them is infuriating.
Don't misunderstand though, this is not an attack on you.
I understand that it is hard to let go of people that you desperately want in your life. You treasure them and you want to be around them but they haven't changed their ways and let's be real, they probably won't change, not the way you want them to so the best decision for all of us is to just let go.
I know that sometimes in relationships, be it romantic or platonic, people hurt you and you forgive them for it and that's completely understandable. Forgiveness is an attribute that only mentally strong people possess. It is when people start taking your forgiveness for granted that you should be worried.
The quote by Bob Marley comes to mind: "The truth is, everyone is going to hurt you. You just got to find the ones worth suffering for."
Do I agree with it? Partially yes.
There are people worth suffering for but if they are really worth it, they will try their best to not hurt you again. If this "if statement" isn't fulfilled, or in other words, if the person says they aren't going to do something that hurts you but does it again without fail, then it's time to leave. They may not be worth suffering for.
We have to realize that some people will be worth suffering for, and some people won't be.
It's a very touchy subject; people say that "you've changed." But in all honesty: you can't fix anybody.
Your loyalty can help them along their journey and be a part of their growth process, but at the end of the day, it's hard to "fix" and heal someone.
What frustrates me the most these days is watching my friends still hang out with people who have hurt them in the past. I can't do anything about it myself because I do not like to meddle in another person's affairs but it frustrates me to no ends.
It can be better to hold a person accountable. Clearly, your "being nice" has not motivated them to change or act appropriately so you need to make sure that they understand that what they are doing is unacceptable. Making a decision to cut a person out of your life may be hard but in some circumstances, it is the only way to move on from that hurt and pain that you have been feeling.