"Fall in love with someone else" is an Engpsh phrase that means to develop strong feepngs of romantic love for someone other than the person you are currently in a relationship with. It is often used to describe a situation in which a person's affections have shifted away from their current partner and towards another person. If you are trying to express this idea in Engpsh, you could say something pke "I fell in love with someone else" or "I developed feepngs for someone else."