Transitioning from Client to Friend

Does anyone else have this problem? Is it a chick thing? I think I owe much of my success to the fact that I have a warm personality and really like to bond with my clients. It really just happens without concious effort. During the transaction, I gain their trust and their loyalty and I develop an awesome relationship. I'm a nurturer by nature (probably should have had more kids!) and make sure my clients needs are taken care of, all very professionally.  After close of escrow, I keep up with my past clients through calls, mailings, emails and the occasional lunch. This works for many clients. But how do you make the transition smooth for those clients that really want to continue the contact? At some point, we have to move on so I can take care of the needs of current clients. I surely don't want to offend by avoidance. Is there a smooth way to transition from the attentive agent to the past professional?