For me, I idealize my romantic interests and strangers, but not my friends. I am actually pretty hard on my friends. If they do something unethical, I sort of make a mark in my mental database and see if it is acceptable or not based on the wider context, their other traits, etc.
None of my friends have ever betrayed me, but I keep a very small close-knit circle. I do have friends who forgives people easily - she's ESFP. For her, I think she needs that constant stimulation and what she deems forgivable is different from what I deem forgivable. What is forgivable for her is completely unacceptable for me. And what she finds unacceptable, I was puzzled by it.
Because of my past, I am very cynical and hold very low expectations of people so I am constantly on guard. My over-cynicalism is actually causing me a great deal of anxiety. I have to remind myself that they are not doing it to hurt me or make me mad - it's just a logical step that makes complete sense in their framework. Instead of being mad at everyone, I am learning to set up my own boundaries and enforcing those boundaries so I know what is okay by me, and they know what is okay and what is not instead of just pushing people out.
I do have a weaker, blurry spot for serious romantic interests though but that happens like once every two-three years. I do ask for my friends' opinions regarding that but I am touchy about it as I have my own logical framework. For me, I need to come to my own conclusions.