Better than most Harlequins, though I've read the novel and they had definitely broken up before he slept with the other woman, but the manga makes it seem like full on cheating by omission which I didn't like.
Although the level of understanding between the FL & ML was better in the manga than the novel.
The WTF?! It was sooo abrupt and so just... Unsatisfactory! The sudden mutual feelings totally didn't feel believable. Such great art I expected more development