Blood is Thicker than Principle

I had a chat with a friend, we were talking of our brother's on how both of them had more than 1 GF at a time during their college days. My friend didn't like the idea as it was morally wrong, I didn't like the idea as well and I also think it is wrong. But , this is where we had differences in opinion, I would not tell on my brother and would cover up for him if he wished me to, as in my opinion blood is thicker than principle in some cases. My brother was wrong in doing so but I would still take his side out of love. My opinion lang.