I think relationships are okay as a teen but not until you are around 15, you wouldn't be mature enough until around that age.
Also most people who have relationships as teenagers tend to date people who are in there circle of friends so they sill see everyone like normal.
My cousin first got together with his girlfriend when he they were 13, they are now 17 and still together, so not all relationships end after a few months.
Also they live in different villages so they spend weekends with each other but hang around with their friends during weekdays. They also go out with each others friends on weekends (depending on who's house they are at) so they have gained friends from it.
It depends on how close you are aswellm me and my ex were best friends then we started dating about 3 years ago(while we were 13) we broke up this year but are still good friends.This is because we have the same circle of 30ish friends so we still see each other often.
But each relationship is different so it all depends on the situation.
I may have mentioned only good thing above but for every good story there are 5 bad ones.