Cesare de Como (Red Hair) & Isabella de Mare (FL half sister) betrayed FL in the first timeline
Ariadne of Mare (FL) help Cesare murder the Crown Prince, Alfonso de Carlo (ML/Blonde Hair) in the past
Alfonso & Isabella were married (arranged marriage) in the past
Seems like FL still "loves" Cesare in the current timeline for now/in the beginning
Cesare & Alfonso will have rivalry for power and love
Alfonso (ML) is in love with FL (first sight)
FL wants get revenge on Isabella
Lastly looks like Cesare & Isabella only loved each other in the past since they have no Present Timeline arrow indicating their relationship
It's not mention in the diagram but Cesare and FL were engaged but never married in the past
He's not fully mention but Raphael is another important character he seems to be the 3rd ML