Moral Muteness

There was one time in my life that always comes to mind when i think of times i should have spoken up about something that was wrong but didn't. My best friend from home had a girlfriend of 4 years. He always talked about how much he was miserable with her but we all thought he was just saying that to sound cool and that he actually did really like her. Right when we graduated high school we went on a senior trip to the outer banks where we met up with this group of kids and we knew like two out of the 12 kids who were living in that house. He hooked up with one of the girls in that house all week and my best friends sister right before we left (which i found out later). He continued to hook up with this girl he met at the outer banks when we got back and just hid it from his girlfriend. Now being his best friend and the fact they dated for 4 years i knew his girlfriend very well and thought she was really nice. I never said anything to her and found out that last week they broke up cause their relationship had been deteriorating for the last year or so. Maybe if i had just spoken up at that time they could have avoided being together for a year where they didn't even like each other anymore. But also would have been crossing a moral line to tell when my best friend since i was 5 told me to keep it a secret. But looking back on it i believe they both would have been better off if i had told her.