Well I am guilty of this, but it has always occured when I have also been in the company of others as a group. It would have been awfully rude of me to have been rude, ignorred, or unpleasant to that individual I really didn't care for. Yes, I try to be fair and pleasant out of a sense of obligation to do so. Another example is the whole staff or office thing. I will treat everyone fairly even those I can't stand or I don't think deserving. I don't think I've ever said to someone I don't care for "I don't like you" "I don't want to spend time with you" etc. I've been snubbed numerous times myself which is perhaps why I am reluctant to do the same.

On another note, are you constantly evaluating acquaintanceships and looking for something wrong? I came to the realization I was doing this. It was as though I couldn't accept that I was likeable and tried to find a negative message in everything. These days I try to be more positive and seek out what is good.