We can agree that having a slight dating preference is not racist. Implicit Association Testing reveals that I have a preference for dark-skinned people, yet I married a white woman because we became friends, then fell in love.
Refusing to consider the possibility you might fall in love with someone outside of your racial preference is racist. Boyega said, "I only date Black." That's no different than a KKKer saying "I only date White." It's gone beyond a preference to a principle that comes from race reductionism.
I haven't seen any "question marks thrown up" about Hollywood couples with a white man and a black woman, but maybe I hang out on a different part of the internet than you.