It’s fairly possible it was more for Vanessa Kirby and Harper’s Bazaar that she actually tagged and for sure has some kind of publicity arrangement going on (Hello unchanged Twitter / Tumblr header!) than for The Crown. After all, there’s plenty of pics of Vanessa Kirby she could have tweeted but she chose this cover and I don’t think it’s random.
So I don’t know if she’s still with that guy or not, but there’s hope!