First off, the series mentions very briefly about the very short lifespan friendship between the prince and the ML when both were little children. This series is definitely NOT about how the FL breaks up the non-existent friendship between the prince and the ML.

Considering that the FL went back in time and met the ML first, not the prince, it sounds fair that the FL and ML got together again and again, while the prince tried his best to steal the girl, using any excuses he could, fair or not. (The prince character seems weak, narrow minded & stupid at times. I am glad the FL didn't go for him, even if this FL character happens to be very dumb, who constantly made horrible mistakes and caused troubles for others.)

My guess is, the prince character gets jealous with the ML character perhaps since the time they were little children (hence the prince's tendency to constantly find fault with the ML, his mean schemes to get rid of the ML). Leave it alone, the prince wouldn't be bother looking twice at the FL, but seeing her with the ML triggered his competitive & petty nature.

The ML played his role very well. The FL was just so so.

The plot was a bit messy. The story was not told well here, a pity! Side characters & their romance or whatever else, took too much screen time, which dragged and dragged...

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Just re-watched some episodes. Sounds like FL sacrificed herself (by breaking the flute) so that ML could wake up and live. They re-united in the end (the implication was there with ML after travelling everywhere to search for FL, finally saw FL's back at a cottage, waiting for him). At the palace, the prince (turned out he was ML's younger brother) seemed to get the present version of FL, since the younger girl practically followed him around (like FL had used to follow ML in their previous life).