Matching all hardware finishes?

We are in the design phase and trying to make final design decisions. We’ve selected grey shaker cabinets and I love the look of black handles against the doors. I’m okay with a black faucet but my designer is saying that if I go with a black faucet I need to get a black sink. At the moment I am leaning towards a stainless undermount sink so most people would never see the mismatch.

Do I really need to match the sink and faucet and handles or is some mismatch ok?