Breaking up is not the end of the world. Don't do anything crazy to hurt yourself or others. Talking out your hurts with a friend, parent or adult who you trust can help. In any case, realize that responsibility comes with love. You must be mature enough to accept obligations to yourself, your loved one, and your family.
Sex adds even more responsibility to a relationship.
An unplanned pregnancy and bad grades may not seem terrible right now, but could ruin the rest of your life. Sex alone cannot make a relationship work. Sex is not love. Teenage marriages have an extremely high divorce rate. It is unrealistic to think that marriage may solve any problems that you have with your parents, in a relationship, or in school.