My major role is as a customer relationship manager; the most important thing is to align the customer's expectation with reality.

Once a customer's expectation is in-line with with can be done, and how long that will take, and how much it will cost, and when it can be used in production, you have one happy customer, even if they are unhappy with the projected start date, or the projected cost (generally a deal-breaker, so that's why I align that upfront with ballparks).

You can listen all you want, empathise all you want, but the reality is the reality - they have to acknowledge and/or accept the realities.

Having a customer relationship manager who agrees to everything the client wants is going to result in one very unhappy customer. The customer-interface person needs to listen to both the client and the internal team, to make sure what the client expects is what your team can actually deliver.