This plot hole only actually applies to both Musa which is only in Season 8 in that Star of Harmony episode that is not Musa but it also applies to Erendor Sky's Father from his being to Bloom upon her visit to Eraklyon and being mad, to yelling furiously at Brandon, and in magical adventure clearly that apology was fake and he is still very jealousy that Oritell is more popular than him and this keeps leading him to trust the wrong people leading him to hire Diaspro over and over again when she's proven to be the most horrible person for the wrong kind of job and a person who holds a grudge so strongly they often tend to ignore the people who tell them they need to let it go and stop trying to be overcontrolling with others. Erendor completely ignores his wife's advice which tells me Samara has little say as Queen of Eraklyon's kingdom ever since we met her. Eraklyon is a male dominated ruled world. Bloom coming into it begins to change that because she makes vital decisions others can't because they're afraid of Erendor or just won't change because Eraklyons except for Sky don't seem to be okay with change. This irritates Erendor to the core and he wants to payback her back in spite throughout every 2- 3 seasons. He spites her in the episode where they meet, He spites her in Season 4 and Magical Adventure with the fake apology, and why is it fake because Magical Adventure takes place Mid Season 4 cause it has to because the Tree of Life is introduced in Season 4 episode 2 and that is still how the Winx found Roxy and if the Tree of Life was destroyed Roxy would have no reason to be around she would be erased and the Wizards of the Black Circle wouldn't have returned to Earth, period Skylights. The fact that Erendor goes back on his word once is a clue he'll go back on it again and again in later scenes. Speaking of which Erendor never shows up with Sky to the Renewal life ball of Domino but I'm 100% sure Oritell invited him given he had absolutely no knowledge of Erendor's betrayal until reading all that was in the crystal container and that flashback Sky tells us is Erendor's first step of gojng back on his word which foreshadows that he keeps slipping backwards and doesn't stay true to his word.
While Musa only has one episode where does act totally out of the character from the one we've gotten to know Erendor's done it multiple times from Season 2-5 and I bet Oritell was convinced Marion to invite Erendor in the Season 6 party where Oritell finally crowns Daphne Erendor doesn't show up in fact I wouldn't be surprised if off screen he gave the unwanted invitation to Diaspro and let her go in his place. To me this is what feels to be happening.
Musa still has the opportunity to change but for Erendor the best redemption for him is permanent death.
While Musa is only an 8 in abusive control Erendor is a 10 at it, Skylights.