Just because people break up it doesn't mean that what they had was real, or that their feelings were false. People aren't obliged to only like one person forever. Humans love many people, they even love two people at the same time without being aware of it. Jesus they can even date someone and love her more than anything and still love someone else too.
And i'm a girl, so i bet that many girls think this way too. It's just a relationship, and you have a whole life, take it easy.