It's wrong to love someone other than your partner.
Sara is in a relationship but has been getting emotionally close to a friend.
Sara wants to deepen her relationship with the friend.
Sara decides to end the relationship with her partner before pursuing the friend.
Sara allows her relationship with the friend to deepen emotionally and falls in love with him while still in a relationship.
Sara's partner is able to move on and find someone who loves him.
Sara's partner is led on and continues to think she only has feelings for him.