I agree, but that also came out of nowhere. Why does he pull away during their kiss? He literally says he loves her two seconds before that! The secret of his parentage is out, there's no reason now for them not to be together.
And then he doesn't even say anything to explain or to soothe her feelings. The woman he supposedly loves is feeling hurt and rejected and he just stands there like a lump because D&D can't write dialogue to save their lives.
The she says the line about fear, and he still doesn't say anything! Forget their personal relationship, this is "his queen" announcing that she tends to terrify Westeros into supporting her, and he has nothing to say about that as one of her main advisors? It's bad writing, pure and simple.
And I still can't buy that any of that would be enough to make Dany start butchering innocents. It's telling that D&D chose to stop showing her on Drogon's back as she flamed her way across the city. They knew that if they actually showed her face it would be obvious it was wildly OOC for her to keep doing this for over half an hour. I could maybe buy a momentary impulse followed by instant regret, but methodical, relentless slaughter of thousands of innocents who surrendered? No way.