In ancient stories and fables there’s always a character that appears as one thing at the start of the story, usually an apparent steadfast friend, but who changes when tested. Some clients certainly fall into this category.
The client who wants to be so friendly: Hail fellow well met, can’t do enough for you. We’ve all meet them, and some of us have been shafted by them. They are your friend, until there’s a problem, then all of a sudden they are siding with their employer. Or the client manager who’s a great supporter of the project until you hit rough water and then they are the project’s most vocal detractor: these are shape shifters.
Project managers should never get closer to the client than they are to their own team. Remember you are in a contractual relationship with the client. You may appear to be working for him in many ways, but your not, the man who signs your paycheck always as first call on your loyalty. So by all means be friendly, it sure beats the alternative. But, it’s a business relationship. Keep it that way.