I don’t think so. I think that the phrase arose from wishful thinking. People are, in my opinion, full of surprises and if you actually could know someone too well, you would be able to anticipate their moods, reactions, likes and dislikes and etc.I don’t actually know anyone who can say that. I don’t know myself too well, so I don’t see how I can know someone else too well. My husband sometimes complains that if I knew him better, I wouldn’t do or say the thing that made him mad. My answer is always, “I didn’t think that you would get mad at that, sorry”. Moreover, most people evolve or change over time, they either get more rigid or less rigid with life experiences. I think that it’s rare for someone to stay the same over time. The basic core stays true but the outer layers tend to flow with encounters with people, different challenges and opportunities.
Do we really want to know anyone too well? Where would the dynamism, intrigue and surprise be in relationships? Learning something new or even a degree of different in someone in your life keeps you on your toes and reminds you to the business of cultivating a relationship. Relationships are like gardens, they need work, might not need daily work, but work is required and even with the same level of maintenance your most constant plants can occasionally give you a surprise, welcome or not. I think that people are similar, you often think that they will so or say one thing and then they go and surprise you. That may be where the saying taking someone for granted came about, and it is not a positive saying. It implies thinking that you know someone too well and not doing the necessary work to keep the relationship healthy. I think that actively getting to know someone better over time keeps the appreciation for the person alive and the relationship valued at the same time. This sounds great on paper but then life gets in the way and we do what we do, which is all individual. And you never know what that may be, do you?