The 19-year-old star - who has been dating Justin Bieber since December 2010 - admitted when she is with a person she loves she "always" wants to make the relationship work, but she has learnt to accept that she can`t change people.
She said: "I believe in second chances, but I don`t believe in third or fourth chances. I love talking through things and always want to make things work if I really love someone.
"But if they can`t fix whatever is wrong, they`re probably not going to change for anybody. You can`t change a person, so sometimes you have to move on."
The `Wizards of Waverley Place` actress explained while she thought her first break-up was "the end of the world", she has since moved on to "better" things.
Selena added: "When I went through my first break-up I thought it was the end of the world. So what did I do? I cried it out, screamed and called my friends in the middle of the night. But that`s OK.
"You have to let it be painful and get through it. Just remember that every day gets better."