I got used to this when she was guesting frequently on Arrow but I totally feel you, here. Her American accent is pitch fucking perfect but damned if it didn't take some getting used to.
It's funny... Romance is definitely not my primary genre of interest in fiction. There's a lot of romance I enjoy but I'm very picky if that's the main genre for a story. If it's an element in a scifi story (or whatever) I'm all good usually but "supernatural romance", "romantic comedy", etc...I get real particular. But when a romance hits me just right and I get into it, it hits me hard. I have rewatched these first 5 episodes at least a half dozen times and the scenes pertaining to the romance itself even more than that. And I keep fiending for the next episode to hurry up and drop already. They got my number hard core.