John Fowles's
The Collector (not a Romance) was written with two POV's. First the butterfly collector's POV - I can't remember if he used the 1st or 3rd person for this chap; next he retold the story from the victim's POV, in the form of diary entries (in the 1st person, obviously). Finally, he reverted to the butterfly collector's POV.
Because he divided the story into 3 clear sections there was no problem with changing POV at these points. And because we were in the heads of two different people, we got quite different views of the same events. I did not find this repetition
boring, but, on the contrary, illuminating and engrossing. But the story was presented deliberately that way and readers knew, or soon discovered, that he was going to explore the minds of an obsessive and his victim as the plot unfolded.
Fowles did not mix POV's within these sections however. The butterfly collector could only surmise his victim's thoughts in his parts of the book, and she could only guess at his thoughts in hers.
TYWD