Splitting

Hi,
I do alot of black and white thinking and put people in these categories, but only with people who are important to me. I have a very good friend, I always liked him alot, but he did things which hurt me and I put him on the bad side. He became nice again and I forgave him and I gave explanations why he might have acted this way. I cannot deal with this abivalent acting (in my eyes) and now I just characterized him as not so important person for me. This way it is much easier to deal with him and this way I can mentally tolerate good and bad sides. How can I tolerate both side in a person which is important for me (as he actually is)?