What you're experiencing is normal, wonderful and honest - first love.
Yes - there are people who meet at 13 and end up married as adults - but it's not something that you need to know right now. If the 2 of you are that rare couple - you'll know that in the future and you'll both feel good about the decision.
Relationships are choices that two people make together - and individually each and every day.
The choice facing both of you today is to have a healthy relationship that's good for both of you. That can be very scary. It does mean allowing each other to be typical teens, to change, to doubt, to want to spend time apart, to pursue different paths and to disagree while respecting each other's right to have ideas the other doesn't. ...yeah - that can be tough. It's the true test of maturity though.
As for heartbreak - that doesn't just come from breaking up with someone. Heartbreak is a normal part of life. Your heart will break the first time a beloved family member passes, a best friend moves away, your child says something mean,.... Even though it hurts, it also helps to make you into someone who can feel sympathy and understand others. Don't be afraid of this. Hearts break. They mend. You get stronger each time.
There is no age for love it can be in early age too.
Feel free and live with your love :)