Anime similar to Nina the starry bride, Raeliana and 7th time loop?

Need a shoujo with royalty. Would like it to be on the more serious side rather than comical. I love protective and stoic male characters like Noah from Raeliana, azure and sett , Arnold from 7th time loop. I've tried taming the final boss but found it too comical and the romance was too fast for me. I prefer a slow burner